J-NRLF 


B    3    3DD    fifiD 


n 


THE  CHILDHOOD   O 
ANIMALS 

I  3TAJ1 

83TAMIM  OMUOY  TO  1UOHO 

,99xn.6qmiiiO  £  OIB  iri^h  ot  itel  moil  ,9ld£^  arit 
t9q^t  nBirujrl  n£3qoiu3  .(absYorn^S)  aqy^  n^murl 
£  llal  9ilJ  o*  ,fonuoi^9iol  sill  nl  .anfitu-gnBiO  owJ 


PLATE  I 

GROUP  OF  YOUNG  PRIMATES 


Behind  the  table,   from  left  to  right  are  a  Chimpan/ 
Asiatic  human  type   (Samoyede),  European  human  type, 
and  two  Orang-utans.      In  the  foreground,  to  the  left  a 
Gorilla,  to  the  right  African  human  type  (Nigerian). 


THE  CHILDHOOD   OF 
ANIMALS 


THE    CHILDHOOD   OF 
ANIMALS 


BY 


P.  CHALMERS   MITCHELL 

M.A.,  LL.D.,  D.Sc.,  F.R.S. 


ILLUSTRATED   WITH   TWELVE   COLOURED   PLATES   FROM    PAINTINGS 

BY  E.   YARROW  JONES,   M.A.,  AND  WITH   MANY  FIGURES 

IN  THE  TEXT    FROM  PENCIL  DRAWINGS 

BY   R.    B.    BROOK-GREAVES 


NEW  YORK 

FREDERICK  A.  STOKES  COMPANY 

PUBLISHERS 


BIOLOGY 
LIBRARY 


Prais'd  be  the  fathomless  universe, 

For  life  and  joy \  and  for  objects  and  knowledge  curious. 

WALT  WHITMAN. 

J'ai  Pamour  de  la  raison,  je  n'en  ai  pas  le  fanatisme. 

ANATOLE  FRANCE. 

Then  sing,  ye  Birds,  sing,  sing  a  joyous  song  ! 

And  let  the  young  Lambs  bound 

As  to  the  tabor's  sound  ! 
We  in  thought  will  join  your  throng, 

Ye  that  pipe  and  ye  that  play, 

Ye  that  through  your  hearts  to-day 

Feel  the  gladness  of  the  May  1 

W.  WORDSWORTH. 


PREFACE 

IN  December  and  January  of  1911-1912  I  delivered  the  Christmas 
Course  of  Lectures,  "  adapted  to  a  Juvenile  Auditory/'  at  the 
Royal  Institution  of  Great  Britain,  and  took  as  my  subject  "  The 
Childhood  of  Animals/'  The  six  lectures  were  not  written ;  they 
shaped  themselves  as  the  course  proceeded,  partly  in  relation  to 
the  set  of  lantern-slides,  specimens  and  living  animals  that  I  was 
able  to  bring,  and  partly  in  accordance  with  the  advice  of  my  kind 
and  experienced  friend  Sir  James  Dewar.  This  book  is  not  a 
printed  version  of  the  lectures,  although  it  tells  the  same  story  in  a 
different  fashion.  A  lecture  must  be  as  direct  and  as  little  cumbered 
with  detail  as  may  be ;  the  leaves  of  a  book  can  be  turned  back- 
wards and  forwards,  and  its  lines  skipped  or  re-read.  I  have 
therefore  been  able  to  include  many  details  that  I  had  to  omit  when 
I  was  speaking,  and  to  cover  my  canvas  in  a  different  way.  In 
particular,  I  am  no  longer  trying  to  address  a  juvenile  auditory  ; 
I  have  attempted  to  avoid  the  use  of  terms  familiar  only  to  students 
of  zoology,  and  to  refrain  from  anatomical  detail,  but  at  the  same 
time  to  refrain  from  the  irritating  habit  of  assuming  that  my  readers 
have  no  knowledge,  no  dictionaries  and  no  other  books. 

My  object  has  been  to  bring  together  observations  old  and  new  that 
seemed  to  throw  a  light  on  the  nature  of  the  period  in  the  life-history 
of  animals  between  birth  and  maturity,  rather  than  to  write  a  formal 
treatise  on  the  subject.  I  have  not  found  it  possible,  nor  have  I 
tried  to  keep  strictly  within  the  logical  confines  of  the  title.  Where 
the  subject  seemed  to  lead,  there  I  have  followed  cheerfully, 
remembering  that  I  am  not  preparing  readers  for  an  examina- 
tion where  no  marks  will  be  assigned  to  extraneous  matter. 

It  has  been  pleasant  to  collect  the  material,  pleasant er  when  it 
seemed  possible  to  arrange  it  so  as  to  display  a  rational  interpreta- 
tion, perhaps  most  pleasant  when  the  unruly  facts  refused  to 
conform  with  theory.  Although  it  may  be  true,  as  Lord  Morley 
once  wrote,  that  the  universe  will  never  cease  to  be  "a  sovereign 
wonder  of  superhuman  fixedness  of  law/'  it  is  at  least  a  mitigating 

vii 


viii  PREFACE 

circumstance  that  as  the  laws  are  superhuman,  we  need  not  be 
quite  certain  that  we  know  them.  Pleasure  in  her  ways,  rather  than 
a  cold  comprehension  of  them,  is  Nature's  surest  gift  to  us,  and  I  am 
content  if  I  have  provided  a  setting  of  theory  sufficient  to  make  the 
facts  lustrous. 

I  am  deeply  indebted  to  Mr.  E.  Yarrow  Jones,  who  prepared  the 
beautiful  designs,  painted  on  Japanese  silk,  which  have  been 
reproduced  as  the  plates  in  this  volume.  I  was  anxious  to  obtain 
the  co-operation  of  an  artist  who  would  see  the  animals  with  his 
own  eyes,  adopt  his  own  decorative  formula,  and  not  be  content 
with  setting  down  diagrams  giving  the  data  of  colour  and  form  that 
we  find  useful  in  treatises  on  systematic  zoology.  I  confess  that 
my  delight  was  tinged  with  surprise  when  I  found  Mr.  Jones's 
art  revealed  individual  and  specific  characters  which  cannot  be 
described  by  words  and  diagrams.  I  have  also  to  offer  my  sincere 
thanks  to  Mr.  R.  B.  Brook-Greaves  for  his  patience  and  skill  in 
making  the  pencil-drawings  for  the  text-figures. 

Finally  I  have  to  state  my  indebtedness,  in  general  terms,  to  the 
great  army  of  writers  on  zoological  subjects.  To  have  tried  to 
attribute  to  its  proper  source  each  observation  that  I  have  used, 
or  each  little  piece  of  half-remembered  theory,  would  have  over- 
weighted this  book  with  historical  pomp,  and  puffed  out  its  slight 
figure  to  unhealthy  repletion.  Although  there  are  some  observations 
that  are  new,  I  claim  credit  for  the  mode  of  presentation  rather  than( 
for  what  is  presented. 

P.  CHALMERS  MITCHELL 

LONDON,  August  21,  1912 


CONTENTS 


CHAPTER  PAGE 

PREFACE  vii 

I.  CHILDHOOD  AND  YOUTH  i 

II.  LARVAE  AND  METAMORPHOSES  17 

III.  THE  DURATION  OF  YOUTH  IN  MAMMALS  37 

IV.  THE  DURATION  OF  YOUTH  IN  BIRDS  AND  LOWER  ANIMALS           49 
V.  COLOUR  AND  PATTERN  IN  ANIMALS  62 

VI.  COLOURS  AND  PATTERNS  OF  YOUNG  MAMMALS  81 

VII.  COLOURS  A*TD  PATTERNS  OF  YOUNG  BIRDS  97 

VIII.  LIMITATION  OF  FAMILIES  115 
IX.  BROOD-CARE   AND    LIMITATION    OF    FAMILIES    IN    LOWER 

VERTEBRATES  i 34 

X.  BROOD-CARE  IN  BIRDS  14? 

XI.  BROOD-CARE  AMONG  MAMMALS  163 

XII.  THE  FOOD  OF  YOUNG  ANIMALS  183 

XIII.  THE  TAMING  OF  YOUNG  ANIMALS  204 

XIV.  THE  PURPOSE  OF  YOUTH  222 
XV.  EDUCATION  239 

I  DEX  257 


ix 


LIST  OF  PLATES 

PACK 

I.  Group  of  Young  Primates  Frontispiece 

II.  Giraffes  and  Young  To  face     10 

III.  Lion,  Lioness  and  Cub  62 

IV.  Lady  Amherst's  Pheasants  :  Cock,  Hen  and  Chicks  68 
V.  Red  Deer  :   Stag,  Hinds  and  Fawn  92 

VI.  American  Tapir  and  Young  94 

VII.  King  Penguins  and  Young  104 

VIII.  Sea-gulls  and  Young  162 

IX.  Female  Capped  Langur  Monkey  and  Young  164 

X.  Female  Black-headed  Lemur  and  Young  166 

XI.  Black-necked  Swans  with  Cygnets  240 

XII.  Springbuck  and  Young  250 


LIST  OF  ILLUSTRATIONS 

PAGE 

1.  Part  of   the  marsupial  pouch  of  the  Red  Kangaroo,  with 

young  attached  3 

2.  Reproduction  of  Amoeba  5 

3.  Head  of  an  unborn  Gorilla  8 

4.  Head  of  a  Human  Foetus  9 

5.  Head  of  an  unborn  long-nosed  Ape  9 

6.  Young  cub  of  American  Timber-wolf  10 

7.  Three  stages  in  the  growth  of  Takin's  horns  13 

8.  Tadpole  of  a  Frog  18 

9.  Metamorphosis  of  an  Ascidian  20 

10.  Metamorphosis  of  the  Sole  22 

11.  Larvae  of  a  Starfish  23 

12.  Metamorphosis  of  Polygordius  25 

13.  Larvae  of  a  Gastropod  Mollusc  26 

14.  Larvae  of  the  crustacean  Penaus  29 

15.  Larva  and  Pupa  of  Blow-fly  31 

1 6.  Caterpillar  and  chrysalid  of  Privet  Hawk-moth  32 

17.  Larvae  and  Pupa  of  the  Oil-beetle  33 

1 8.  Development  of  a  Locust  35 

19.  Metamorphosis  of  Mexican  Axolotl  60 

20.  Repetition  Pattern  64 

21.  Bilateral  Ink  Pattern  65 

22.  Oyster-catcher  79 

23.  Young  and  Adult  Banded  Duiker  Antelope  89 

24.  Young  and  Adult  Selous'  Sitatunga  Antelope  90 

25.  Down-plumage  Patterns  107 

26.  Sea-urchin  carrying  its  young  119 

27.  Brittle-star  carrying  its  young  120 

28.  Male  Hippocampus,  showing  brood-pouch  137 

29.  Darwin's  Rhinoderma,  showing  brood-pouch  141 

30.  Ring-tailed  Lemur  carrying  its  young  167 


Xlll 


xiv  LIST  OF  ILLUSTRATIONS 


PAGE 


31.  Hippopotamus  carrying  its  young  172 

32.  Tree-hyrax  carrying  its  young  174 

33.  Tree-kangaroo  with  young  in  pouch  179 

34.  Koala  carrying  its  young  181 

35.  Opossum  carrying  its  young  181 

36.  Brains  of  Primates  227 


CHAPTER  I 
CHILDHOOD  AND  YOUTH 

WE  look  out  on  the  world  with  human  eyes,  and  see  with  little 
wonder  whatsoever  is  like  ourselves.  We  are  born,  small  and 
helpless,  yet  visibly  stamped  with  humanity  ;  day  by  day  we 
change,  but  move  with  certainty  in  one  direction.  A  few  years 
pass,  and  from  childhood  we  attain  youth,  a  few  more  and  we 
reach  maturity.  The  changes  affect  size  and  structure,  character 
and  disposition,  but  are  so  orderly  and  familiar  that  we  accept 
them  without  surprise,  and  demand  for  them  no  explanation.  Man 
is  only  one  of  many  hundreds  of  thousands  of  living  species,  and 
living  beings  are  only  a  small  part  of  the  world  around  us.  Is  the 
mode  by  which  man  attains  manhood  universal  in  the  living  world, 
and  does  the  living  world  differ  in  this  respect  from  things  that  are 
not  alive  ? 

The  universe  throbs  with  restless  change.  Our  sun  with  its  system 
of  revolving  planets  is  rushing  into  the  recesses  of  starry  space  on 
some  errand  at  which  we  cannot  guess.  The  little  planet  that  is  the 
home  of  the  only  life  we  know  is  impermanent  in  its  masses  and 
in  its  details.  The  oceans  shift  on  their  uneasy  beds  ;  continents 
and  islands  rise  and  fall.  Mountains  and  plains  are  carved  and 
fretted  by  air  and  wind  and  water,  blistered  by  heat,  riven  by 
frost,  and  smoothed  over  by  vegetation.  The  chemical  elements  of 
which  we  used  to  think  as  eternal  counters,  passing  unchanged 
through  mazes  of  combination  and  disintegration,  are,  some  of  them 
at  least,  in  a  process  of  making  or  unmaking.  Everything  that 
we  know  is  becoming  rather  than  being.  None  the  less  there  are 
degrees  and  differences  in  change  itself.  The  swift  and  inevitable 
routine  of  life  stands  in  sharp  contrast  with  the  vaguer  and  more 
capricious  rhythms  of  things  that  are  not  alive.  All  living  creatures 
are  born  into  the  world  from  seeds  or  eggs  or  directly  from  the 
bodies  of  their  parents,  and  unless  they  meet  death  by  the  way,  meet 
it  at  the  end,  after  passing  through  childhood  and  youth,  maturity 
and  old  age.  This  orderly  progress  from  the  beginning  to  the  end  is 

C.A.  A 


#  .  r :: :  CHILDHOOD  OF  ANIMALS 

characteristic  of  all  animals,  and  the  parts  of  it  that  we  call  childhood 
and  youth  are  the  most  characteristic.  Complicated  pieces  of 
machinery,  like  watches  or  motor-cars,  resemble  animals  in  many 
ways,  and  like  them  may  be  new  or  old,  but  are  never  young. 
Youth  is  a  property  of  the  living  world. 

The  history  of  an  animal,  from  its  first  appearance  as  a  speck 
of  living  matter  formed  from  the  parental  body,  to  its  death,  is 
continuous,  and  it  would  be  useless  to  try  to  define  exactly  when 
childhood  begins,  when  it  passes  into  youth,  or  the  point  at  which 
the  period  of  youth  ends.  There  is  difficulty  even  in  fixing  the 
beginning,  for  animals  of  the  same  kind  may  be  born  at  different 
stages  of  growth,  whilst  animals  of  different  kinds  differ  extremely 
in  this  respect.  A  large  black  newt,  brilliantly  spotted  with  yellow, 
known  as  the  spotted  salamander  and  common  in  the  south  of 
Europe,  lays  eggs  like  the  spawn  of  a  frog.  But  unlike  the  eggs  of  the 
frog  which  show  the  presence  of  tadpoles  only  after  some  days,  those 
of  the  salamander  appear  with  fully  formed  little  tadpoles  wriggling 
in  them,  and  hatch  almost  as  soon  as  they  are  laid.  Sometimes 
they  hatch  actually  before  they  are  laid,  and  it  is  in  the  tadpole 
stage  that  the  animals  first  appear  in  the  world.  So  also  most 
snakes  lay  eggs  and  incubate  them  for  days  or  weeks,  before 
the  young  snakes  break  through  the  leathery  shell.  But  in  some 
snakes,  like  the  common  adder,  what  corresponds  to  hatching  takes 
place  inside  the  body  of  the  mother,  and  instead  of  eggs  being  laid, 
young  snakes  are  born.  Most  of  the  warm-blooded,  hairy  creatures 
that  we  know  as  mammals  because  they  suckle  their  young,  give 
birth  to  moving  young  and  do  not  lay  eggs,  but  two  of  them,  the 
duck-billed  platypus  and  the  spiny  echidna  of  Australia,  lay  eggs 
with  yolk  and  hard  shells.  The  platypus  incubates  the  eggs  until 
they  hatch  ;  the  echidna,  after  laying  an  egg,  transfers  it  with  her 
mouth  to  a  pouch  on  the  under  side  of  her  body,  like  that  of  a 
kangaroo,  and  in  this  warm  and  secure  receptacle,  safer  than  any 
nest,  the  egg  is  kept  until  it  hatches.  Mammals  of  the  group 
known  as  Marsupials,  because  most  of  them  have  a  marsupium,  or 
pouch  (which  is  well  seen  in  the  kangaroo),  at  one  time  laid  large 
eggs  and  no  doubt  transferred  them  with  the  mouth  to  the  pouch,  just 
as  the  echidna  still  does.  But  now  the  eggs  are  retained  for  a  certain 
time  in  the  body,  although  the  young  are  still  very  imperfect  when 
they  are  born.  The  new-born  young  of  a  kangaroo  is  less  than  an 
inch  long,  although  its  mother  may  be  nearly  as  tall  as  a  man.  The 
figure  (Fig.  i)  has  been  drawn  from  a  specimen  obtained  at  the 


CHILDHOOD  AND  YOUTH  3 

London  Zoological  Gardens,  and  shows  the  naked  little  creature,  an 
embryo  rather  than  a  young  animal,  hanging  to  a  nipple  inside 
the  hairy  pouch  of  its  mother.  In  higher  mammals  eggs  are  not 
laid,  and  the  young  at  birth  are  much  more  formed  than  in  the  case 
of  the  kangaroo,  but  they  may  be  covered  with  fur,  have  their  eyes 
open  and  be  able  to  run  in  a  few  minutes,  like  young  hares,  or,  like 
young  rabbits,  may  be  naked,  blind  and  helpless.  Even  in  one 
species  there  may  be  notable  differences  ;  the  kittens  in  a  single 
litter  are  seldom  alike  in  size,  in  the  degree  of  their  development  and 
in  the  date  when  they 
begin  to  see,  and 
although  new  -  born 
human  babies  are 
more  closely  similar, 
some  may  be  at  least 
a  month  older  or  a 
month  younger  than 
usual,  and  yet  grow 
up  quite  normally. 
These  differences  are 
interesting  and  im- 
portant, but  I  men- 
tion them  here  only 
to  show  that  there  is 

no  exact,  fixed  point  FlG.  lt  part  of  the  inner  wall  of  the  pouch  of  the  red 
in  its  history  when  kangaroo,  with  the  young  attached  to  the  teat. 

.     ,.    .  ,      ,  (Natural  size.) 

a      new     individual 

ceases  to  be  an  egg  or  an  embryo  and  may  fairly  be  called  a  young 
animal. 

In  the  same  way  the  end  of  the  period  of  youth  is  indefinite.  Some- 
times there  is  a  sharp  break.  A  caterpillar  becomes  a  chrysalid  and 
from  the  chrysalid  the  full-grown  moth  or  butterfly  emerges.  Some- 
times, perhaps  more  often,,  the  transition  is  gradual.  Even  the  time 
when  a  young  animal  itself  canbecome  a  parent  does  not  give  a  dividing 
line.  A  few  generations  ago,  girls  were  thought  fitted  for  marriage 
when  they  were  fourteen,  and  not  infrequently  became  mothers 
whilst  they  were  still  children.  Amongst  animals,  parentage  is 
often  precocious  in  individuals  or  in  whole  groups.  We  must  be 
content  to  take  the  period  of  youth  in  a  general  way  as  a  subject 
for  description  rather  than  for  precise  definition. 

Young  animals  can  be  placed  in  three  groups,  notably  different  in 


4  CHILDHOOD  OF  ANIMALS 

their  character.  The  first  group  has  little  claim  to  existence  ;  it 
contains  a  few  animals  that  have  no  period  of  youth.  The  second 
group  contains  very  many  of  the  animals  with  which  we  are  most 
familiar.  The  young  are  sufficiently  like  their  parents  to  enable  us 
to  make  a  close  guess  as  to  what  they  are  going  to  become.  We 
have  no  doubt  that  a  human  baby  is  a  young  human  being,  that  a 
baby  monkey  belongs  to  the  group  of  monkeys,  although  we  may 
not  be  quite  certain  as  to  the  particular  species  of  which  it  is  a 
member.  It  is  the  same  with  kittens,  puppies,  calves  and  lambs  ; 
we  place  them  at  once  among  the  mammals,  with  complete  certainty 
in  their  own  order,  and  with  a  probability  that  depends  on  our 
powers  of  observation  and  knowledge  in  their  proper  family,  genus, 
or  species.  Young  birds  may  puzzle  us  a  little  more,  but  at  the 
least  we  are  never  in  doubt  that  the  naked  or  fluffy  creatures  are 
going  to  be  birds.  Crocodiles  and  lizards,  snakes  and  turtles 
similarly  come  into  the  world  with  their  relationships  plainly  stamped 
upon  them. 

In  the  third  group  we  must  place  those  young  animals,  of  which 
many  insects  and  marine  creatures  are  familiar  types,  that  are 
so  unlike  their  parents  that  their  destiny  cannot  be  guessed  from 
inspection.  The  changes  through  which  many  of  these  creatures 
pass  on  their  way  to  adult  life  are  as  strange  as  if  a  new-born 
human  baby  were  to  have  the  form  of  a  fish,  swimming  in  a  tank, 
feeding  greedily  on  worms  and  water-fleas,  and  then  after  a  few 
weeks  or  months  were  to  grow  very  fat  and  sleepy,  to  split  along 
the  back,  and,  discarding  its  fish-skin,  to  creep  out  on  land  in  the  form 
of  a  hedgehog  ;  and  if  the  hedgehog  were  to  live  for  months  or  years 
the  life  of  a  humble  quadruped,  growing  bigger  and  fatter  until  it 
too  reached  a  limit  of  growth,  broke  out  of  its  hedgehog  skin  and 
appeared  as  an  adult  human  being  fitted  in  body  and  mind  to  be  a 
bishop  or  a  burglar. 

It  is  not  to  be  supposed  that  these  three  different  kinds  or  aspects 
of  youth  agree  with  the  divisions  in  which  the  animal  kingdom  is 
arranged  by  zoologists.  It  happens  that  the  creatures  without 
a  true  period  of  youth  belong  to  the  lowest  division  of  animals,  and 
that  the  highest  animals  fall  naturally  into  the  second  group,  but 
the  vast  range  of  living  beings  between  the  lowest  and  the  highest 
divisions  show  all  degrees  of  close  likeness  and  complete  unlikeness 
to  their  parents.  Nor  must  it  be  supposed  that  the  three  groups  are 
sharply  marked  off.  The  arrangement  of  facts  in  groups  is  more 
convenient  than  natural,  and  we  must  not  forget  that  many  of  the 


CHILDHOOD  AND  YOUTH  5 

divisions  of  science  are  concessions  to  the  human  mind  rather  than 
forms  of  nature. 

Further  consideration  of  the  first  group  need  not  detain  us 
long.  The  very  small  animals  known  as  amoebae  (Fig.  2),  the 
largest  of  which  are  visible  as  specks  to  the  naked  eye,  are  mere 
droplets  of  granular  protoplasm,  creeping  over  the  mud  in  fresh 


M 

I 


-. ,-- 


m 


FIG.  2.     Reproduction  of  Amoeba  (highly  magnified).     To  the  left  a  full-grown 
amoeba ;  to  the  right  successive  stages  of  division. 

water  or  in  the  sea,  or  lurking  in  the  bodies  of  other  animals  or  of 
plants.  The  soft,  jelly-like  material  of  which  they  are  formed 
makes  it  possible  for  little  particles  of  food  to  be  engulfed  wherever 
these  come  in  contact  with  the  surface  of  the  body.  The  simple 
business  of  their  life  is  to  creep  in  search  of  food,  to  digest  the  food 
as  quickly  as  possible,  and  to  grow  bigger.  But  although  the 
different  kinds  of  amoeba  differ  in  size,  there  is  a  limit  beyond 
Which  each  kind  does  not  grow.  When  that  limit  has  been  reached, 
or  sometimes  before  it  has  been  reached — for  reproduction  is  a  good 
deal  more  complicated  in  its  causes  than  a  mere  escape  from  incon- 


6  CHILDHOOD  OF  ANIMALS 

venient  size — the  amoeba  becomes  oblong  in  shape  and  then  acquires 
a  kind  of  waist  which  becomes  more  and  more  slender  until  only  a 
string  of  jelly  remains.     Finally  this  string  divides,  and  the  two 
halves  become  rounded  again,  each  forming  a  complete  amoeba, 
exactly  like  the  parent  in  all  respects  except  size,  and  these  two 
at  once  set  about  the  pursuit  of  food  and  begin  to  grow.     The 
two  amoebae  may  be  called  young  animals  in  the  sense  that  they 
have  just  come  into  existence  as  new  individuals,  but  nothing  in 
their  tissues  or  characters  distinguishes  them  from  their  parent.     So 
far  as  the  period  of  youth  has  any  interest  or  significance,  these 
animals  escape  it.    Many  small  creatures  belonging  to  the  lowest 
group  of  the  animal  kingdom,  the  Grade  known  as  Protozoa,  repro- 
duce like  amoeba  by  a  process  of  simple  division,  and  it  is  tempting 
to  suppose  that  this  method  is  older  than  the  more  complicated 
fashions  in  which  most  animals  multiply.     Even  amongst  Protozoa, 
however,  very  many  animals  begin  their  individual  lives  in  a  form 
unlike  that  of  their  parents,  and  attain  the  adult  condition  only 
after  passing  through  complicated  changes.     I  am  not  going  to 
describe  any  of  these  here,  as  they  show  no  characters  of  youth 
that  are  not  equally  well  displayed  in  animals  easier  to  observe.     I 
wish  to  recall  their  existence,  however,  because  it  is  very  frequently 
the  case  in  the  living  world  that  simple  structures  and  events  are 
not  primitive,  and  it  may  well  be  that  the  Protozoa  without  a  true 
period  of  youth  are  not  surviving  relics  of  primeval  life,  but  are 
forms  that  have  become  simple  and  degenerate  because  of  the  easy 
conditions  in  which  they  live. 

The  animals  in  the  second  group  will  engage  most  of  our  atten- 
tion in  this  book,  because  they  include  ourselves  and  those  most 
nearly  akin  to  us.  As  their  structures,  habits,  and  dispositions 
are  not  very  remote  from  our  own,  they  offer  problems  which  it  is 
possible  to  understand,  and  perhaps  to  solve,  and  they  give  a  hope 
of  interpreting  our  own  history  and  of  predicting,  perhaps  controlling, 
our  own  future.  They  have  this  in  common,  that  the  young  always 
resemble  the  parents  more  or  less  closely. 

Amongst  human  beings  and  monkeys,  the  young  are  born  in  so 
advanced  a  condition  that  we  think  of  them  as  babies  and  not  as 
embryos.  The  eyes  are  open,  the  voice  is  lusty,  the  face,  the  hands 
and  feet,  and  the  body  generally  are  shapely  and  well  formed.  But 
the  senses  are  deficient,  especially  in  the  great  apes  and  man.  The 
hand  of  a  new-born  infant  will  close  round  and  cling  to  a  broom- 
stick or  any  other  object  placed  in  it,  almost  in  the  automatic 


CHILDHOOD  AND  YOUTH  7 

fashion  in  which  the  tendril  of  a  creeper  will  twine  round  a  support 
which  it  comes  to  touch.  So  also,  in  the  danger  of  the  woods,  the 
new-born  gorilla  or  chimpanzee  must  cling  from  the  first  to  the  body 
of  its  mother,  or  perish  miserably.  In  a  few  days  the  observing 
and  reflecting  parts  of  the  brain  awaken,  automatic  action  becomes 
less  important,  and  is  replaced  by  a  medley  of  instinct  and  intelligence. 
In  the  lower  monkeys,  and  especially  in  lemurs,  although  the  young 
cling  to  their  mothers,  the  automatic  period  is  shorter,  and  the 
babies,  almost  from  the  first,  show  what  looks  like  conscious, 
independent  movement.  Human  babies  and  the  babies  of  apes 
and  monkeys  differ  from  their  parents  in  proportions.  The  heads 
are  relatively  larger,  especially  in  the  higher  creatures,  and  the 
legs  and  arms  are  relatively  shorter.  They  all,  as  a  rule,  are  born 
with  some  hair,  but  this  is  more  scanty  and  more  different  in  texture 
and  colour  than  that  of  the  parents  in  human  beings  and  the  great 
apes,  more  like  that  of  the  parents,  in  abundance,  texture  and  colour, 
in  the  lower  monkeys  and  lemurs.  Special  growths  of  hair,  like 
beards  and  crests,  special  patches  of  colour  on  the  face  and  body, 
like  the  brilliant  scarlet  and  blue  on  the  face  of  the  mandrill,  are 
absent.  I  need  not  waste  time  recalling  familiar  differences  like 
the  absence  of  teeth,  and  of  bony  ridges  on  the  head,  the  softness  of 
the  bones,  the  protruding  stomachs  and  the  general  plumpness  and 
roundness  of  the  body. 

I  have  already  said  of  this  group  of  young  animals  that  although 
there  is  a  fairly  close  resemblance  with  the  parents,  we  cannot 
always  be  certain  of  the  particular  species  to  which  an  infant 
belongs.  The  reason  of  this  difficulty  lies  in  the  striking  circum- 
stance that  the  young  of  nearly  allied  animals  are  much  more  alike 
than  are  the  adults.  No  one  could  fail  to  distinguish  a  fully 
grown  man,  gorilla,  orang  and  chimpanzee,  but  in  many  points  in 
which  the  young  of  these  creatures  differ  from  the  adults,  they 
resemble  each  other  more  closely.  In  the  slow  development  of 
every  individual  before  birth  and  after  birth,  the  characters  of  the 
species  are  the  last  to  be  assumed.  We  explain  this  by  supposing 
that  the  evolution  of  the  individual  to  a  certain  extent  repeats  the 
evolution  of  the  race.  Man,  the  gorilla,  the  orang  and  the  chim- 
panzee had  a  common  ancestor,  and  the  children  of  these  creatures 
are  more  like  the  common  ancestor,  and  so  like  each  other,  than  are 
the  adults.  We  have  to  remember,  however,  that  this  explanation 
is  not  complete,  and  we  shall  find  many  characters  of  young  animals 
to  which  it  does  not  apply.  The  young  animal  owes  its  characters 


8 


CHILDHOOD  OF  ANIMALS 


not  merely  to  its  ancestry  ;  as  much  as  the  adult,  it  has  to  be  fitted 
to  the  special  environment  in  which  it  lives.  It  is  not  merely  a  stage 
in  development,  but  an  independent  living  creature  with  its  own 
needs  and  its  own  aptitudes,  presenting  characters  that  are  neither  a 
memory  nor  an  anticipation,  neither  a  relic  of  the  past  nor  a  pre- 
paration for  the  future,  but  suitable  for  its  own  purposes.  These 


•'•-:• 
FIG.  3.    Head  of  an  unborn  gorilla.     (After  J.  DENIKER.) 

creatures,  suckling  their  mothers,  clinging  to  them  and  being  pro- 
tected by  them,  have  an  environment  which  is  much  simpler  and 
more  nearly  identical  than  the  environment  of  the  adults,  and  we 
must  expect,  quite  apart  from  common  inheritance,  to  find  common 
characters  due  to  common  conditions.  The  figures  on  the  first 
coloured  plate  (see  Frontispiece)  represent  young  animals  two  or  three 
years  old,  and  show  how  much  more  alike  they  are  when  they  are 
still  children  than  when  they  are  grown  up.  The  young  gorilla,  with 
its  small  ears  and  short  upper  lip,  is  not  very  different  in  appear- 
ance from  a  black  baby  ;  the  very  long  upper  lips  of  the  orang  and 


CHILDHOOD  AND  YOUTH  9 

chimpanzee  and  the  large  ears  of  the  latter  make  them  rather  less 
human. 

The  parental  stages  of  man  and  the  great  apes  are  still  more  alike 
than  are  the  young  creatures.  The  text -figures  of  the  young 
gorilla  (Fig.  3),  taken  from  a  specimen  of  an  unborn  ape  obtained 
by  Monsieur  J.  Deniker,  and  of  a  human  being  of  about  the  same 
age,  after  a  figure  given  by  Professor  Metchnikoff  (Fig.  4),  show  the 
almost  appalling  resemblance  between  man  and  the  ape  before  birth. 


FIG.  4.     Head  of  a  human  foetus,  about 
five  months  old.  (After  "E.  METCHNIKOFF.) 


FIG.   5.    Head  of  an  unborn  long- 
nosed  ape.     (After  E.  SELENKA.) 


For  comparison,  I  have  given  in  another  figure  (Fig.  5)  a  representa- 
tion of  a  corresponding  stage  in  the  development  of  one  of  the  lower 
monkeys,  the  long-nosed  ape  of  Borneo,  taken  from  a  drawing  given 
by  Professor  Selenka  in  his  great  monograph  on  the  embryology  of 
mammals.  The  face  and  features,  the  domed  forehead  covering  the 
capacious  brain,  the  practical  absence  of  hair,  and  every  minute 
detail  of  the  internal  and  external  structure  agree  with  a  fidelity  that 
is  almost  shocking.  Professor  Metchnikoff  was  so  impressed  by 
such  resemblances  that  he  has  suggested  that  the  human  race  may 
have  taken  its  origin  from  the  precocious  birth  of  an  ape.  His 
theory  may  be  regarded  rather  as  a  parable  than  a  definite  scientific 
proposition,  but  it  puts  in  a  striking  fashion  a  remarkable  character 
displayed  by  young  animals.  When  these  differ  from  the  adults, 
it  is  not  merely  that  they  resemble  their  ancestors,  or  are  specially 


CHILDHOOD  OF  ANIMALS 

fitted  for  the  purpose  of  their  own  stage  of  life.  They  sometimes 
suggest  the  future  possibilities  of  the  race,  directions  in  which  the 
race  may  move.  As  the  young  animals  mature  they  lose  promise 
and  flexibility,  and  settle  down  to  the  average  characters  and  average 
limitations  of  their  kind. 

Young  Carnivores  seldom  differ  notably  from  their  parents.  The 
cubs  of  lions,  tigers,  leopards  and  jaguars,  and  the  kittens  of  cats, 
lynxes  and  caracals  can  usually  be  identified  at  a  glance.  They 


FIG.  6.     Young  American  timber-wolf. 


are  softer  and  more  rounded,  and  differ  in  size  and  in  proportions,  and 
they  do  not  display  characters  limited  to  one  sex,  like  the  mane  of 
the  lion,  or  special  marks  like  the  twisted,  hairy  tufts  on  the  tips 
of  the  ears  of  caracals  and  lynxes,  and  those  which  are  uniformly 
coloured  when  they  are  adult  may  be  spotted  when  they  are  young. 
The  puppies  or  cubs  of  dogs,  dingoes,  wolves,  jackals  and  foxes  are 
much  more  alike  than  the  adults,  and  point  clearly  to  descent  from 
a  common  and  not  very  distant  ancestor.  Young  wolves  (the 
drawing  in  Fig.  6  represents  the  cub  of  an  American  timber-wolf)  are 
quite  like  the  puppies  of  domestic  dogs,  except  that  their  ears  are 
erect.  The  difference  is  mental  rather  than  physical.  When  they 
begin  to  run  about,  they  betray  a  shy  and  furtive  disposition,  as  if 
they  expected  no  kindness  or  toleration  from  man.  Young  hyaenas 
and  civets,  bears,  raccoons  and  weasels,  seals  and  sea  -lions  all  closely 
resemble  their  parents. 


PLATE  II 

GIRAFFES  AND  YOUNG 


he  colorations  of  the  young  and  the  adult  are  practically 
identical,  but  the  neck  and  forequarters  of  the  young  are 
relatively  shorter.  By  an  accident  of  the  drawing,  the 
vertical  rails  in  the  background  make  the  necks  of  the 
adults  appear  rather  shorter  than  they  are,  but  the  pro- 
portions are  correct  by  measurement. 


.DHOOJ 

»f  the 


• 

TS,  leopa 
als  can 


IT 

OKI  JOY  CT/IA 

9*6  tii/bxj  o/ft  b  ••  ;O  gnoilmoloo  orfT 

SIB  gnuoy  srfi  lo  8i9i-iJ5np9iol:  -  ^rJCf 

arfi   .^nfWBib  orit  lo  JnsI).  a     .i0j"{ 

arfi  lo  a:rfo9fl  oift  9>l6m  bni/OT^>Ioj,d  o;i  n 

-oiq  9rit  iud  ,oiJ3  Yorf* 

.Inamo  ;oq 


:1  more  rounded,  and 

display  characters  li 

r  special  marks  like  the 

f  caracals  and  lynx 
i  when  they  are  adult  ma 

cubs  of  dogs,  ding- 
alike  than  the  adul; 
and  not  very  dist.'i 
"ig.  6  represents  the 

s  of  do*  are 

e  is  mci 
they  b< 

-lions  ai 


CHILDHOOD  AND  YOUTH  II 

It  would   be  tedious  to  go  through  mammals  group  by  group, 
making  the  same  general  statements  about  them.     Differences  of 
colour  and  pattern  in  the  coat  are  often  remarkable  and  will  be 
discussed  in  a  separate  chapter  (Chapter  VI).    When  the  adults  have 
no  special  weapons  or  ornaments,  they  can  be  distinguished  from 
their  young  by  little  that  is  visible,  except  size.    A  young  hippo- 
potamus, except  for  the  absence  of  tusks,  a  young  dromedary  or 
bactrian  camel,  except  that  the  humps  are  not  so  conspicuous,  and 
a  kangaroo,  as  soon  as  it  is  able  to  leave  the  pouch  of  its  mother, 
are  almost  ludicrously  exact  miniatures  of  their  parents.     Baby 
elephants  are  more  interesting.    The  smallest  that  I  have  seen 
was  a  female  Indian  elephant,  presented  to  the  London  Zoological 
Gardens  by  the  Government  of  the  Federated  Malay  States,  and 
certainly  less  than  a  year  old  and  about  three  feet  in  height.     No 
one  could  mistake  it  for  anything  but  an  elephant,  but  it  was 
thickly  covered  with  long  coarse  hair,  recalling  its  distant  relative, 
the  extinct  hairy  mammoth.     Its  ears  were  much  larger  in  propor- 
tion to  the  size  of  the  head  than  in  the  adult  Indian  elephant,  so 
recalling  the  African  animal,  and  this  resemblance  was  increased 
by  the  smoothly  rounded  forehead,  passing  in  an  even  curve  from 
the  root  of  the  trunk  to  the  top  of  the  head,  and  showing  no  sign  of 
the    angular  forehead  of  adult  Indian  elephants.     Its  trunk  was 
rather  short,  the  tip  being  well  off  the  ground  when  the  little  animal 
was   standing  upright,  and  was  rather  an  embarrassment  to  it.     It 
found  difficulty  in  finding  its  mouth  with  it,  fumbling  as  a  baby  does 
when  trying  to  use  a  spoon.     Nor  had  it  learned  to  use  it  in  drinking  ; 
it  sucked  its  milk  by  a  rubber  tube  placed  in  its  mouth,  holding  its 
trunk  awkwardly  out  of  the  way.    No  doubt  if  we  could  see  together 
a  young  Indian  elephant,  a  young  African  elephant  and  a  young 
mammoth,  we  should  find  that  they  were  as  much  alike  as  are  the 
young  of  the  great  apes  and  man. 

A  young  giraffe  (see  Plate  II)  from  the  first  resembles  its  parents, 
but  neither  its  neck  nor  its  legs  are  so  long  in  proportion,  and  the 
horns,  although  erect  and  tufted  with  hair  like  those  of  the  adult, 
are  soft  because  they  have  no  bony  core.  In  the  great  assemblage 
of  animals  that  are  armed  with  horns  or  antlers  the  peculiarities  of 
these  weapons  appear  gradually,  and  the  young,  at  first  defenceless, 
produce  little  straight  spikes  like  those  of  their  fossil  ancestors,  and 
these,  as  they  grow  larger,  curve  or  twist  or  branch  until  they  reach 
the  full  splendour  of  maturity.  In  antelopes,  sheep,  goats  and 
cattle,  where  the  horns  are  "hollow,"  that  is  to  say,  where  they 


12  CHILDHOOD  OF  ANIMALS 

consist  of  a  horny  case  fitting  over  a  bony  core,  the  first  weapons 
to  appear  persist  throughout  life,  however  they  may  increase  in 
size  and  change  in  shape.  In  Fig.  7  some  of  these  differences  are 
shown.  The  takin,  a  rare  and  very  large  goat -like  animal  from  the 
highlands  of  Asia,  shows  little  conical  horns  when  it  is  a  few  months 
old.  These  are  placed  rather  far  apart  on  the  forehead,  separated 
by  an  expanse  of  hair.  As  the  horns  grow  they  acquire  a  spiral, 
goat -like  twist  and  the  greatly  expanded  lower  portions  meet  in  the 
middle  line  to  form  a  stout  rough  helmet.  In  the  eland,  one  of 
the  largest  of  the  African  antelopes,  the  horns  first  appear  as  still 
more  slender  conical  spikes,  and  as  they  grow  usually  become  twisted 
in  a  straight  spiral  in  the  fashion  in  which  a  stick  of  soft  candy  can 
be  twisted  when  one  end  is  held  firm  and  the  other  rotated.  Cattle  of 
different  kinds  also  show  small  spiky  horns  at  first,  and  these  later 
on  acquire  the  spreading  curves  of  the  adult. 

The  change  in  the  kinds  of  horns  we  know  as  antlers,  and  which 
are  found  amongst  deer,  are  even  more  interesting.  Antlers  are 
shed  and  renewed  annually,  and  except  in  the  reindeer  are  carried 
only  by  the  males.  In  young  male  fawns,  a  pair  of  bosses,  covered 
by  the  hairy  skin  and  consisting  of  outgrowths  of  the  bones  of 
the  skull  on  the  forehead  above  the  eyes,  appear  very  soon.  Early 
in  the  first  season  a  bony  knob  is  formed  on  the  summit  of  each 
boss  and  can  be  felt  as  a  warm  and  tender  swelling.  It  grows 
very  quickly  and  in  a  few  weeks  each  has  become  a  short  spike  still 
covered  with  the  layer  of  skin  which  contains  many  blood-vessels 
and  is  known  as  the  velvet,  because  of  its  soft  and  hairy  surface. 
When  the  growth  is  nearly  complete,  a  ring  of  bone  is  formed 
under  the  velvet,  near  the  base  of  the  antler,  and  by  its  pressure  stops 
the  circulation  of  blood  in  the  skin.  The  velvet  then  peels  off,  the 
deer  assisting  in  the  process  by  rubbing  the  antlers  against  the  bark 
of  trees,  and  when  the  bloody  surface  has  dried  up,  there  is  left  the 
burnished  antler,  with  its  brown  and  roughened  surface  forming  what 
we  know  as  deer's  horn.  At  the  end  of  the  season  these  antlers  are 
shed,  breaking  away  from  the  bony  bosses  of  the  skull.  Next  year, 
and  in  each  successive  year,  they  are  re-formed  by  exactly  the  same 
process,  and  in  the  simpler  kinds  of  deer  grow  a  little  larger  each 
year  but  without  much  change  of  shape.  In  other  deer,  however, 
each  antler  may  branch,  producing  a  second  point  or  snag,  and  year 
after  year  when  the  new  antlers  are  produced,  they  may  develop 
additional  points  until  noble  heads  such  as  those  of  fine  red  stags  are 
droduced,  with  as  many  as  forty  points  on  each  antler.  Young 


CHILDHOOD  AND  YOUTH  13 

deer,  then,  of  species  with  branching  antlers  take  a  number  of  years, 
very  nearly  corresponding  with  the  number  of  points,  to  acquire  the 
full  development  of  their  kind,  and  the  antlers  they  produce  in  their 


FIG.  7.  Three  stages  in  the  growth  of  the  horns  of  the  takin.  A,  at 
six  months  old  ;  B,  at  two  years  old  ;  c,  young  adult.  (From  an 
example  living  in  the  London  Zoological  Gardens. ) 

earlier  years  resemble  those  of  the  simpler  kinds  of  deer,  and  also 
of  their  extinct  ancestors. 

Mammals,  when  they  are  born  or  very  soon  afterwards,  closely 
resemble  their  parents.  The  differences  are  due  to  greater  likeness 
to  ancestors  and  to  their  nearest  allies,  to  the  absence  of  special 
weapons  or  ornaments,  or  to  the  presence  of  characters  useful  to  the 
young  themselves. 

Newly  hatched  birds,  nestlings  and  fledglings  are  usually  rather 


I4  CHILDHOOD  OF  ANIMALS 

unlike  their  parents,  but  none  the  less  fall  into  the  second  group  of 
young  animals.  The  shape  of  the  body,  the  head  with  its  bill  and 
long  neck,  the  wings,  the  absence  of  a  true  tail,  and  the  single  pair 
of  legs  with  the  slender  toes  leave  us  in  no  doubt  as  to  the  group  of 
the  animal  kingdom  to  which  the  most  naked  chick  belongs.  Those 
with  only  a  slight  knowledge  of  the  families  into  which  birds  are 
divided  are  able  to  tell,  from  the  shape  of  the  head  and  the  beak, 
and  the  number,  arrangement  and  formation  of  the  toes,  whether 
the  young  creature  is  a  perching  bird,  a  parrot,  a  bird-of-prey,  a 
wader,  a  duck  or  goose,  or  some  kind  of  fowl  or  pheasant.  Ornitho- 
logists who  have  a  minute  acquaintance  with  the  structure  of  birds 
could  place  the  young  bird  more  accurately,  but  even  the  most 
expert  would  sometimes  make  mistakes  and  often  be  at  a  loss. 
The  difficulty  is  due  to  many  reasons.  The  first  is  ignorance.  Eggs 
and  nestlings  are  a  succulent  prey  for  an  innumerable  host  of 
enemies,  such  as  flesh-eating  mammals  of  all  kinds,  and  many  reptiles 
and  even  other  birds.  And  so  the  nests  and  eggs  and  young  are 
protected  by  innumerable  devices.  They  are  carefully  hidden  or 
placed  in  inaccessible  spots  ;  they  are  shaped  or  coloured  so  as  to 
be  invisible  against  their  natural  background.  The  parents  visit 
them  by  stealth,  protect  them  with  fury,  or  cunningly  mislead  those 
in  search  of  them.  Eggs,  moreover,  and  the  skins  of  mature  birds 
are  objects  that  are  beautiful  and  attractive  in  the  cabinet  of  a 
collector,  or  in  the  cases  of  a  museum,  and  not  difficult  to  prepare 
and  to  preserve.  But  nestlings  and  fledglings,  even  when  they  can 
be  got,  must  be  kept  as  draggled  little  objects  in  spirits  of  wine, 
a  delight  only  to  the  expert  naturalist.  I  should  like  to  add  that 
although  memories  of  boyhood,  the  human  zest  for  sport  and  avidity 
for  knowledge  steel  the  heart  of  the  naturalist  collecting  eggs  or 
birds,  there  is  an  appealing  quality  of  confident  helplessness  about 
nestlings  that  few  could  resist.  I  have  seen  a  German  professor 
putting  young  fishes  into  hot  pickle  with  tears  on  his  face,  but  the 
born  collector  of  young  birds  is  generally  hanged  for  more  lucrative 
crime.  In  any  case,  our  knowledge  of  nestlings  is  defective. 

Even  with  complete  knowledge,  I  doubt  if  young  birds  could  be 
assigned  to  their  proper  species  as  correctly  as  similar  identifications 
could  be  made  in  the  case  of  mammals.  For  all  birds,  in  the  elements 
of  their  structure,  are  closely  akin.  Even  the  great  families  are  diffi- 
cult to  separate,  and  species  are  distinguished  chiefly  by  external 
structures  and  especially  by  the  differences  in  plumage.  Young 
birds  may  be  naked,  and  so  show  nothing  of  the  most  distinctive 


CHILDHOOD  AND  YOUTH  15 

'specific  character ;  they  may  be  downy,  and  the  down  of  many 
different  kinds  of  birds  is  alike  ;  and  they  may  assume  several 
successive  plumages,  none  of  which  are  like  those  of  the  adult. 
Although,  therefore,  they  certainly  belong  to  the  second  group  of 
young  animals,  the  resemblance  with  the  parents  is  seldom  close. 
Young  birds  are  certainly  birds,  and  very  often  the  group  or  family 
to  which  they  belong  can  be  recognised. 

When  reptiles  are  hatched  or  born,  they  are  in  a  much  more 
advanced  state  of  development  than  occurs  in  the  case  of  birds. 
Not  only  is  there  no  doubt  as  to  their  being  reptiles,  but  they  are 
plainly  crocodiles,  lizards,  serpents  or  tortoises,  and  although  they 
may  be  protected  by  their  parents  for  a  time,  they  are  at  once  able 
to  move  and  to  feed,  and  in  their  appearance  and  habits  are  miniature 
copies  of  their  own  parents.  * 

The  three  groups  into  which  I  am  placing  young  creatures  do  not 
correspond  exactly  with  the  different  classes  of  animals,  and  the 
Batrachians  (frogs,  newts,  toads  and  their  allies)  and  the  fishes 
lie  on  the  border-line  between  the  second  and  third  groups.  Some 
frogs,  when  they  are  hatched,  appear  as  little  air-breathing,  terres- 
trial creatures  quite  like  their  parents,  but  most  pass  through 
a  tadpole  stage,  and  tadpoles  not  only  live  very  different  lives  from 
the  adults,  but  differ  extremely  from  them  in  appearance.  So 
also  amongst  fishes,  some  of  the  sharks  hatch  in  a  form  so  like 
their  parents  that  they  can  be  at  once  assigned  to  their  proper 
family  and  even  species,  and  the  young  stages  of  eels  were  known 
and  given  separate  names  as  different  kinds  of  fish  long  before  there 
was  any  idea  that  they  were  young  eels. 

The  multitudinous  tribes  of  animals  without  backbones,  which, 
in  contrast  with  the  Vertebrates  (Mammals,  Birds,  Reptiles, 
Batrachians  and  Fishes),  are  spoken  of  as  Invertebrates,  display 
extremely  different  types  of  structure,  but  agree  in  usually  having 
a  totally  different  appearance  in  the  young  and  the  adult  stages. 
There  are  some  exceptions  ;  young  spiders  resemble  their  parents 
in  the  fashion  of  reptiles  and  mammals,  and  here  and  there  the 
members  of  an  individual  family  or  group  of  invertebrates,  unlike 
their  nearest  relations,  are  hatched  in  a  form  differing  from  the 
adult  chiefly  in  size.  These  exceptions  are  usually  cases  of  animals 
that  have  taken  to  live  in  fresh  water  or  on  land,  in  circumstances 
where  the  kind  of  young  which  is  found  in  their  nearest  allies  would 
have  difficulty  in  surviving.  The  nearest  marine  relatives  of  the  fresh- 
water crayfish,  for  instance,  hatch  out  as  delicate  floating  creatures 


16  CHILDHOOD  OF  ANIMALS 

extremely  unlike  their  parents,  but  which  would  be  carried  away 
by  the  currents  in  brooks  and  rivers.  When  the  young  crayfish  is 
hatched,  it  is  a  miniature  crayfish  which  has  only  to  grow  and  to  make 
a  few  trivial  changes  to  reach  the  adult  form. 

The  young  animals  in  the  second  group  appear  in  the  world  in  a 
form  that  is  more  or  less  like  that  of  their  parents,  and  reach 
maturity  by  increase  in  size  and  by  a  gradual  assumption  of 
the  full  character  of  the  adult.  Incidentally  they  show  various 
structures  and  characters  that  are  of  benefit  only  in  the  period  of 
youth  and  that  have  probably  been  acquired  for  that  purpose.  In 
their  younger  stages  they  often  recall  the  structure  and  appearance 
of  the  younger  stages  of  their  nearest  relations,  and  probably  also  of 
the  ancestors  common  to  them  and  to  their  nearest  relations.  But 
these  ancestral  resemblances  are  vague  and  uncertain  ;  the  young 
animals  do  not  wish  to  display  to  us  their  pedigrees,  but  to  become 
adults  as  quickly  and  as  directly  as  possible.  Although,  however, 
it  appears  to  be  certain  that  animals  do  repeat,  to  some  extent,  the 
history  of  their  race  in  their  individual  lives,  and  compress  into  a 
few  weeks  or  months  the  results  of  countless  centuries  of  evolution, 
we  cannot  expect  the  repetition  to  be  very  perfect.  And  I  think 
we  are  led  to  the  curious  conclusion  that  the  more  directly  an  animal 
develops,  and  the  earlier  it  shows  traces  of  what  it  is  going  to 
become,  the  less  it  shows  of  its  ancestral  history.  The  path  of  evolu- 
tion which  was  slowly  traced  by  the  ancestors  of  the  animals  alive 
to-day,  has  been  long  and  tortuous,  sometimes  direct  for  a  time,  often 
twisting  sharply  to  one  side  or  the  other,  sometimes,  perhaps,  even 
bending  backwards.  So  far  as  it  is  possible,  animals  avoid  these 
devious  ways  in  their  individual  lives  and  press  on  straight  to  the 
goal.  In  the  animal  kingdom  as  a  whole,  and  in  each  of  its  divisions, 
the  higher  types  tend  to  develop  most  directly  and  to  show  least 
of  their  ancestral  history. 

Consideration  of  the  third  group  of  young  animals,  in  which  the 
young  stages  differ  much  from  the  adult  stages,  requires  a  separate 
chapter. 


CHAPTER  II 
AND  METAMORPHOSES 

THE  easiest  way  to  begin  to  get  a  picture  of  the  group  of  young 
animals  which  are  very  unlike  their  parents  is  to  remember  that 
many  animals  now  live  in  surroundings  quite  different  from  those 
of  their  remote  ancestors.  Although  frogs  are  able  to  swim  well 
and  often  are  found  in  water,  they  are  really  land  animals.  They 
have  lungs  and  breathe  air,  they  hop  about  on  land  in  search  of  the 
beetles  and  other  insects  on  which  they  feed,  and  many  of  them, 
especially  the  green  tree-frogs,  never  readily  take  to  water  except 
at  the  breeding  season,  and  others  even  lay  their  eggs  on  land. 
The  ancestors  of  frogs  were  fish -like  animals,  living  entirely  in  the 
water,  with  gills,  not  lungs,  with  a  swimming  tail  and  without  hands 
and  feet.  Probably  in  the  course  of  a  long  period  of  time,  and  while 
they  were  still  aquatic  animals,  some  of  them  began  to  swallow  air 
in  the  way  that  a  number  of  fishes  still  get  an  additional  supply  of 
oxygen,  and  probably  also  some  of  them  had  pouches  on  the  gullet 
into  which  the  air  was  taken,  as  in  the  lung -fishes  which  still  live 
in  the  waters  of  Africa,  Australia  and  South  America.  Many 
different  kinds  of  fish  crawl  on  their  fins  over  the  mud  at  the  bottom 
of  the  water  in  which  they  live,  whilst  others  creep  out  on  the 
edge  of  the  shore  and  hop  along  in  the  surf.  It  is  not  at  all  difficult 
to  follow  in  imagination  the  slow  changes  by  which  such  creatures, 
living  in  shallow  marshes,  became  more  and  more  apt  for  terrestrial 
life  and  thus  truly  amphibious,  capable  of  living  in  water  or  out 
of  it.  A  long  swimming  tail  is  an  inconvenient  possession  on  land. 
Newts  and  salamanders  retain  it,  but  are  seldom  able  to  move 
quickly,  and  the  fortunate  ancestors  of  the  frogs  probably  lost  it. 
The  modern  frog,  however,  instead  of  regaining  amphibious,  makes 
the  change  from  aquatic  life  to  terrestrial  life  quickly,  in  a  few  days. 
It  hatches  out  as  a  tadpole,  a  fish-like  creature  with  the  head  and 
body  in  a  single  mass,  continued  behind  into  a  long  tail  which  is 
adapted  for  swimming  by  the  presence  of  a  thin  web  above  and 
below.  It  has  no  limbs,  and  little  tufts  of  gills  protrude  through 
C.A.  '7  B 


i8  CHILDHOOD  OF  ANIMALS 

a  slit  at  each  side  of  the  neck,  It  finds  its  food  in  the  water,  de- 
vouring greedily  almost  any  kind  of  animal  or  vegetable  matter,  with 
a  pair  of  horny  jaws  made  up  of  a  large  number  of  horny  teeth 
closely  set  together.  So  it  lives  and  grows  for  a  few  weeks.  But 
soon  the  limbs  begin  to  bud  out  (Fig.  8),  and  the  lungs  develop,  while 
the  tail  shrivels,  and  in  an  extremely  short  time  a  number  of  internal 
and  external  changes  take  place,  and  the  tadpole  suddenly  leaves  the 
water  and  becomes  a  frog.  Such  a  striking  change,  associated 
with  a  change  of  habit,  is  called  a  metamorphosis,  and  the  young 
animal,  before  it  has  gone  through  the  metamorphosis,  is  called 
a  larva.  The  method  of  development  is  plainly  a  very  condensed 
and  quickened  repetition  of  the  ancestral  history,  and  the  larva 
is  equally  plainly  the  modern  representative  of  a  remote  ancestor. 
We  must  not  suppose,  however,  that  the  larva  is  the  unchanged 

image  of  the   ancestor. 

The  tadpole,  when  it  is 
^  not  swimming,  anchors 

itself  to  water-weeds  by 

an  adhesive  apparatus, 

a  kind  of  sticky  sucker, 
FIG.  8.     Advan^cedjadpole  of  a  Frog,  with          Qn  the  under  surface  of 

the  head,  just  behind  the 

mouth.  We  have  no  reason  to  be  sure  that  this  organ,  which  differs 
very  much  in  different  kinds  of  tadpoles,  is  a  legacy  from  the  ancestor ; 
it  may  equally  well  be  what  is  called  a  larval  organ,  a  structure 
developed  for  the  benefit  of  the  tadpole  itself.  So  also  the  teeth 
of  the  adult  frog  are  true  teeth,  probably  much  more  like  the  teeth 
of  the  fish  ancestor  than  the  peculiar  horny  jaws  of  the  tadpole. 
These,  too,  may  be  new  organs,  developed  for  the  benefit  of  the 
tadpole.  It  is  probable,  too,  that  the  tufts  of  gills  visible  from  the 
outside  are  new  organs  of  the  larvae,  and  that  another  set  of  gills, 
lying  deeper  in  the  gill-slits,  but  not  present  in  all  tadpoles,  is  the 
true  ancestral  organ  of  respiration.  Every  larva  is  in  this  way  a 
composite  of  organs  and  structures  some  of  which  are  ancestral,  whilst 
others  are  new  and  developed  only  for  the  larva.  In  some  cases,  like 
the  tadpoles  of  frogs,  the  ancestral  element  is  greater,  and  we  may 
well  believe  that  the  larva  is  a  fairly  close  copy  of  the  ancestor.  In 
other  cases,  which  I  shall  describe  presently,  probably  the  greater 
part  of  the  larva  is  new  and  gives  us  no  true  image  of  the  ancestor. 
The  batrachians  which  lose  their  tails,  the  Anura,  or  frogs,  toads 
and  tree-frogs,  show  almost  every  stage  between  a  true  meta- 


LARV.E  AND  METAMORPHOSES  19 

morphosis  and  a  direct  development.  In  most  of  them  the  eggs  are 
laid  in  water  and  true  tadpoles  hatch  out.  In  some  the  eggs  hatch 
on  land,  having  been  laid  in  holes,  on  grass  or  leaves,  and  when 
the  tadpoles  are  hatched,  they  wriggle  into  water  or  are  washed 
into  pools  by  the  rain.  In  others,  again,  the  eggs  are  laid  on  land, 
and  the  tadpoles  have  lost  their  gills  before  they  are  hatched,  but 
^the  metamorphosis  is  completed  later  on.  In  a  few  the  complete 
change  occurs  inside  the  egg,  and  when  hatching  takes  place 
little  frogs  appear,  sometimes,  however,  with  a  stump  of  the  tail 
still  left.  In  others  the  eggs  are  carried  by  the  parent,  and  here,  too, 
they  may  be  hatched  as  tadpoles  or  as  perfect  frogs.  It  would  be 
difficult  to  find  a  better  example  of  the  gradual  change  from  a 
type  of  development  which  is  a  repetition  of  the  ancestral  history, 
to  the  higher  type  in  which  the  young,  as  soon  as  they  assume  active 
life  on  their  own  account,  resemble  their  parents  more  or  less  closely. 
The  metamorphosis  of  the  tadpole  into  the  frog  is  a  change  from 
a  lower  to  a  higher  type  of  life.  The  larvae  of  ascidians  or  sea -squirts 
change  by  metamorphosis  into  an  adult  which  must  certainly  be 
regarded  as  a  lower  form  of  life.  The  eggs  hatch  into  small  tadpoles 
which  swim  actively  through  the  sea  by  vibrating  the  webbed 
tail,  the  latter  being  stiffened  by  a  simple  kind  of  backbone  in  the 
form  of  a  rod  of  tough  jelly.  There  is  a  hollow  spinal  cord,  rather 
like  that  in  the  very  young  tadpole  of  a  frog,  and  in  the  front  of  this, 
•'n  the  region  where  the  brain  of  the  frog's  tadpole  is  developed, 
there  is  a  simple  kind  of  eye  and  ear.  Near  the  mouth  there 
are  adhesive  organs  by  which  the  creature  can  anchor  itself  tem- 
porarily. The  mouth  leads  into  a  wide  gullet  pierced  by  gill-slits, 
some  of  which  at  least  correspond  with  the  gill-slits  of  the  frog's 
tadpole.  At  the  metamorphosis,  the  larva  fixes  itself  permanently, 
at  first  by  the  adhesive  organs,  and  afterwards  by  an  outer  jacket 
or  test  which  covers  the  whole  animal  with  a  protecting  coat.  The 
tail  with  its  representative  of  the  backbone,  the  greater  part  of  the 
nervous  system,  and  the  sense-organs,  disappear.  The  gullet  and 
the  part  of  the  body  surrounding  it  increase  in  size,  until  they  make 
up  the  greater  part  of  the  bulk  of  the  animal.  The  wall  of  the 
gullet  becomes  transformed  into  a  sieve,  pierced  by  innumerable 
holes  through  which  the  sea -water  is  filtered,  leaving  behind  the 
small  particles  which  are  used  as  food.  The  active,  swimming 
larva  (Fig.  9),  with  a  structure  extremely  like  that  of  the  lower 
vertebrates,  changes  in  this  way  into  a  hollow  bag  which  sucks  in 
water  by  one  hole  and  pours  it  out  by  another,  and  which,  if  we 


20 


CHILDHOOD  OF  ANIMALS 


did  not  know  its  history,  we  should  find  very  difficult  to  associate 
with  backboned  animals.  How  far  the  larva  of  the  sea -squirt 
shows  a  repetition  of  the  structure  of  its  ancestors,  or  how  far  its 


. 


FIG.  9. 


9.  Metamorphosis  of  an  Ascidian.  The  upper  figure  shows  the  tadpole 
adhering  to  a  flat  surface ;  the  lower  figure  shows  the  young  Ascidian 
similarly  but  permanently  attached.  (After  LANKESTER,  KOWALEVSKY 
amZHERDMAN;  much  magnified.) 

shape  and  its  organs  have  been  formed  and  adapted  for  the  purposes 
of  its  own  life,  can  only  be  guessed,  and  different  zoologists  have 
made  very  different  guesses.  The  most  usual  interpretation  is  that 
the  larva  is  in  the  main  ancestral,  and  that  the  degradation  of  the 
adult  is  pure  degeneration.  The  sea-squirts  are  taken  to  be  humble 
relations  of  the  vertebrates  which  became  degenerate  because  they 


LARV.E  AND  METAMORPHOSES  21 

had  adopted  the  habit  of  fixing  themselves  to  the  rocks  of  the  coast, 
and  which,  in  the  course  of  their  development,  show  memories  of 
their  high  descent.  But  it  is  also  possible  to  suppose  that  their 
history  has  been  different.  It  would  be  greatly  to  the  advantage  of 
animals  which  are  anchored  in  adult  life  if  their  young  could  move 
about  and  settle  down  in  new,  less  crowded,  and  perhaps  more 
suitable  quarters.  The  swimming  shape  is  no  peculiarity  of  verte- 
brates, and  this  tail  and  the  directing  sense-organs  may  be  new 
characters  acquired  for  the  purposes  of  the  larva. 

Flat-fish  like  the  sole  and  the  turbot  show  a  metamorphosis 
which  is  more  easy  to  understand,  and  which  occurs  when  the  kind 
of  life  led  by  the  larvae  changes  to  that  of  the  adults.  Most  bony 
fishes  have  what  we  think  of  as  the  usual  shape  of  a  fish.  They  are 
symmetrical,  with  the  right  and  left  sides  of  the  body  alike  in  shape, 
colouring,  arrangement  of  the  fins  and  such  paired  organs  as  the 
eyes.  Whether  they  live  near  the  surface  of  the  sea,  or  haunt  the 
bottom,  they  swim  in  the  same  sort  of  position  as  we  do  when  we  are 
using  the  ordinary  breast-stroke,  that  is  to  say,  the  back  is  upwards, 
the  under  side  is  downwards.  The  upper  side,  too,  is  much  more 
darkly  coloured  than  the  white  or  very  pale  under  side.  The  newly 
hatched  larvae  of  turbot,  brill,  halibut,  plaice,  soles  and  other 
flat-fish  have  this  familiar  and  symmetrical  shape  and  coloration, 
and  when  they  begin  to  feed,  pursue  their  small  prey  in  the  water 
exactly  like  other  predaceous  fishes.  When  they  have  grown  to  a 
little  less  than  half  an  inch  in  size,  however,  a  sudden  change  comes 
about.  The  right  and  left  sides  of  the  body  become  very  different. 
In  the  turbot  and  brill  the  left  side,  and  in  the  halibut,  plaice  and 
sole  (Fig.  10 )  the  right  side,  become  dark  in  colour,  whilst  the  other 
side  loses  any  pigment  it  had  and  is  almost  completely  white.  The  eye 
of  the  uncoloured  side  rapidly  moves,  partly  round  and  partly  through 
the  head,  until  it  comes  to  lie  near  the  other  eye  on  the  coloured  side 
of  the  body.  At  the  same  time  other  changes  in  the  shape  of  the 
body  and  the  position  of  the  organs  take  place,  so  that  the  sym- 
metrical larva  becomes  a  distorted  adult,  what  we  would  call  at 
first  sight  the  upper  side  not  being  the  real  back  of  the  animal,  but 
the  right  side  in  some  cases,  the  left  side  in  others.  When  the 
metamorphosis  is  complete,  the  fish  changes  its  habits.  Instead 
of  swimming  freely  through  the  water,  it  lurks  on  the  bottom,  lying 
flat  on  the  sand  or  mud,  with  the  coloured  side  uppermost.  In 
these  cases  there  can  be  almost  no  doubt  but  that  the  larva,  which 
is  like  the  great  majority  of  fish,  is  the  ancestral  form,  and  that  the 


22  CHILDHOOD  OF  ANIMALS 

change  to  the  adult  condition  is  a  condensed  and  rapid  repetition 
of  the  slow  ancestral  history. 

The  forms  of  larvae  and  the  kinds  of  metamorphoses  which  occur 
in  marine  invertebrates  are  many  and  varied,  and  the  few  examples 
I  shall  choose  will  serve,  I  hope,  rather  to  show  the  interest  and 
difficulty  of  the  subject  than  to  beguile  readers  into  thinking  they 
or  I  understand  it.  Echinoderms,  of  which  we  all  know  starfish 
and  brittle-stars,  sea-urchins  and  sea-cucumbers,  crawl  at  the 
bottom  of  the  sea  and  show  a  radiate,  generally  a  five-rayed,  sym- 
metry. That  is  to  say,  the  organs  of  the  body  are  arranged  round 


FIG.  10.     Three  stages  in  the  metamorphosis  of  the  Sole.    (After  FABRE- 
DOMERGUE  and  BIETRIX  ;  slightly  enlarged.) 

a  central  axis,  which  is  short  in  the  flat  echinoderms;  such  as  the 
starfish  and  brittle-stars,  or  long  in  the  globular  and  oblong  ones, 
such  as  the  sea-urchins  and  sea -cucumbers,  like  the  spokes  of  a 
wheel  or  the  petals  of  a  five -rayed  flower.  The  eggs  of  most  of 
these  echinoderms  are  very  small,  and  soon  after  they  are  shed  into 
the  water  grow  into  little  floating  larvae.  The  larvae  quickly  assume 
the  shape  of  a  thick -walled  cup,  the  outside  of  which  is  covered  with 
small,  waving  threads  of  living  matter,  called  cilia,  and  the  hollow 
of  which  forms  the  primitive  digestive  cavity.  The  cup  grows  larger 
and  longer,  and  its  aperture  narrows  to  a  small  pore.  A  new  aperture 
breaks  through  into  the  digestive  cavity  and  becomes  the  mouth  ; 
the  original  aperture  sometimes  closes  up,  sometimes  remains  to 
form  the  posterior  aperture  of  the  digestive  canal.  The  larva 
changes  its  shape,  becoming  flat,  or  even  concave,  on  the  side  where 
the  mouth  and  anus  lie,  and  remaining  dome -shaped  on  the  other. 


LARVAE  AND  METAMORPHOSES  23 

The  flat  side  is  now  the  ventral  surface,  with  the  mouth  not  quite 
at  the  front  end,  the  region  in  front  of  it  being  called  the  pre-oral 
lobe,  the  anus  being  nearly  at  the  hind  end,  and  the  curved  surface 
being  the  back,  or  dorsal  surface  of  the  larva.  The  cilia,  which  at 
first  covered  the  whole  of  the  outer  surface  nearly  equally,  become 
longer  and  stronger  on  a  curved  band  surrounding  the  mouth,  and 
nearly,  or  completely,  disappear  elsewhere.  As  there  is  a  front  end 
and  a  posterior  end,  a  dorsal  and  a  ventral  surface,  and  a  right  and 
left  side,  the  larva  shows  what  is  called  bilateral  symmetry,  and  is 


FIG.  ii.  Larvae  of  a  Starfish  :  to  the  left  a  Dipleurula,  to  the  right  a 
Bipinnaria,  from  the  ventral  surface.  (After  MORTENSEN  ;  much 
magnified.) 

called  a  dipleurula.  These  larvae  move  about  in  the  water  rather 
actively,  propelled  by  the  cilia,  feed  greedily  on  floating  micro- 
scopic plants  and  animals,  and  as  they  grow,  change  into  fantastic 
shapes,  different  in  the  different  groups  of  echinoderms,  and  so 
unlike  the  adult  form  that  many  of  them  were  described  and  named 
before  it  was  known  what  they  were  (Fig.  n).  After  a  few  weeks 
they  become  sluggish,  cease  feeding,  anchor  themselves  to  rocks  or 
weed,  and  pass  into  the  adult  by  a  sudden  metamorphosis,  the 
details  of  which  differ  in  different  species.  It  is  always,  however, 
only  a  part  of  the  larva  that  grows  into  the  adult,  the  remaining 
portion  shrivelling  up,  or  being  cast  off.  In  the  starfish,  for  instance, 
the  attachment  takes  place  by  the  end  of  the  pre-oral  lobe,  which 
forms  a  sort  of  stem  from  which  the  body  of  the  larva  projects,  and 
the  young  starfish  appears  on  the  left  side  of  the  larva,  the  organs 
of  that  side  forming  the  greater  part  of  its  structure,  so  that  the 


24  CHILDHOOD  OF  ANIMALS 

change  from  the  bilateral  symmetry  of  the  larva  to  the  radial 
symmetry  of  the  adult  is  itself  lop-sided  and  unsymmetrical. 

There  can  be  no  doubt  but  that  the  greater  part  of  this  strange 
life -history  of  the  echinoderms,  which  seems  more  like  the  fantastic 
changes  of  a  pantomime  than  the  orderly,  deliberate  processes  of 
nature,  does  not  represent  ancestral  evolution.  The  early  stages 
up  to  the  development  of  the  dipleurula  quite  possibly  recall  the 
structure  of  some  remote  and  primitive  marine  creature  from 
which  not  only  the  echinoderms  but  other  marine  creatures  may  have 
descended,  for  larvae  of  a  similar  type  are  found  in  the  life-history 
of  many  other  animals.  But  the  later  stages  and  the  curious  mode 
of  transformation  into  the  adult  occur  only  inside  the  group  itself. 

Polygordius  is  a  small  worm  which  lives  in  the  sand  farther  out 
than  the  lowest  tide-mark,  rather  in  the  way  that  an  earthworm 
lives  in  the  garden  soil.  It  is  a  bilaterally  symmetrical,  ringed 
creature  with  the  mouth  nearly  at  the  anterior  end,  with  only  the 
portion  containing  the  brain  and  a  pair  of  sensitive  tentacles  in 
front  of  it.  It  swallows  quantities  of  sand,  passes  these  through 
its  digestive  canal,  absorbing  any  contained  food  material. 
The  eggs  are  small,  are  shed  into  the  water  and  soon  grow  into  a 
cup-shaped  larva  very  like  the  early  larva  of  echinoderms.  In 
the  same  way,  the  aperture  of  the  cup  narrows  and  a  mouth  breaks 
through.  The  larva,  however,  then  changes  in  a  different  way.  It 
becomes  shaped  like  a  top,  with  a  tuft  of  sensitive  bristles  repre- 
senting the  upper  pole  of  the  top,  the  narrowed  original  aperture, 
which  becomes  the  anus,  being  at  the  lower  pole,  and  the  mouth 
just  below  the  widest  part  of  the  body.  A  band  of  long  cilia,  called 
the  velum,  passes  round  the  circumference  of  the  widest  part  of 
the  body,  just  above  the  horizon  on  which  the  mouth  is  placed. 
This  larva,  which  has  been  named  a  trochophore  and  which  is  totally 
unlike  the  parent  worm,  swims  about,  feeds  and  grows,  and  then 
suddenly  begins  to  change  (Fig.  12).  The  region  round  the  anus 
grows  out  into  the  long- jointed  body  of  the  worm,  which  hangs  down 
from  the  floating  bell-shaped  larva  like  a  tail,  and  becomes  the 
greater  part  of  the  adult  worm,  soon  growing  to  many  times 
the  original  size  of  the  larva.  The  mouth  of  the  larva  remains  as  the 
mouth  of  the  adult,  and  the  upper  half  of  the  larva  becomes  the 
region  in  front  of  the  mouth  containing  the  brain,  whilst  the  ring 
of  cilia  disappears.  The  worm  drops  to  the  bottom  and  begins  to 
be  a  wriggling  burrower  in  the  sand. 

The  case  of  Polygordius,  which  I  have  taken  as  an  example  of 


i 


F 


FIG.  12.  Metamorphosis  of  Polygordius.  Upper  figure  on  left,  trochophore  larva  ; 
on  right,  later  stage  with  worm  growing  out  ;  lower  figure,  much  more  advanced 
stage,  anterior  end.  (After  PARKER  and  ROULE  ;  much  magnified.) 


26  CHILDHOOD  OF  ANIMALS 

many  similar  cases  in  marine  worms,  is  very  difficult  to  understand. 
If  the  bell -shaped  larva,  swimming  in  the  water  like  a  transparent 
jellyfish,  represents  the  far-off  ancestor,  it  baffles  the  imagination 
to  conceive  the  stages  by  which  this  should  have  evolved  into 
a  creeping  worm,  by  the  elongation  of  the  region  round  its  anus. 
It  is  much  more  simple  to  suppose  that  the  worm  developed  directly 
without  any  floating  larva,  and  that  the  swimming  disk  was  a 
secondary  development  useful,  like  the  wings  of  a  wind-borne  seed,  to 
carry  the  embryo  about.  If  this  be  correct,  the  similarity  between 
the  Polygordius  larva  and  the  larvae  of  other  marine  worms,  with 
the  larvae  of  animals  belonging  to  different  groups  of  Invertebrates, 


•  ,o>. 


FIG.  13.     Larvae  of  a  Gastropod  Mollusc  :  left-hand  figure,  a  Trochophore ; 
right-hand  figure,  a  Veliger.     (Much  enlarged.) 

is,  so  to  say,  a  mere  accident,  due  to  the  similar  lives  the  larvae  lead, 
and  with  little  bearing  on  the  ancestral  relationships  of  these  groups. 
The  large  class  of  Molluscs  contains  animals  of  many  different 
types,  such  as  oysters  and  mussels,  whelks,  snails  and  slugs,  cuttle- 
fish and  squids.  The  period  of  youth  is  passed  under  many  different 
conditions,  and  especially  in  those  that  live  on  land  or  in  fresh 
water  there  are  cases  which  we  can  see,  by  comparison  with 
their  nearest  relations,  to  be  special  adaptations  to  special  circum- 
stances. But  there  are  two  successive  types  of  larvae  found  in  so 
many  different  molluscs  that  it  seems  as  if  they  were  at  one  time 
stages  in  the  life -history  of  all  molluscs.  The  first  is  a  trochophore 
(Fig.  13),  very  like  the  trochophore  of  marine  worms,  and  which 
grows  from  the  egg  in  the  same  way.  It  is  more  globular  than 
top -shaped,  and  the  ciliated  band,  or  velum,  is  nearer  the  upper 
pole,  so  that  the  part  in  front  of  the  mouth  is  smaller  in  proporfion 
than  in  the  worm-larva.  This  rapidly  changes  into  the  second  type 
of  larva,  called  the  veliger,  and  peculiar  to  molluscs.  The  velum  is 
drawn  out  into  branches  or  lobes,  and  the  portion  in  front  of  it  ceases 
to  grow,  so  that  it  becomes  a  mere  swimming  apparatus  carried 


LARVAE  AND  METAMORPHOSES  27 

at  the  anterior  end  above  the  mouth  of  the  larva.  The  body 
develops  a  hump  on  its  back,  and  this  is  soon  protected  by  a  primitive 
shell,  and,  on  the  lower  side,  behind  the  mouth,  a  flattened  mass 
forms  the  beginning  of  the  muscular  foot,  the  slimy  organ  on  which 
a  slug  or  a  snail  crawls.  The  veliger  gradually  assumes  the  shape  of 
the  kind  of  mollusc  in  which  it  is  to  grow. 

It  would  have  required  a  great  deal  of  elaborate  description  and 
the  explanation  of  many  details  of  structure  familiar  only  to  ad- 
vanced zoologists,  to  give  a  just  idea  of  the  remarkable  resemblances 
between  the  larvae  of  Echinoderms,  the  trochophores  of  Worms  and 
Molluscs,  and  the  similar  larvae  of  some  other  marine  invertebrates. 
It  is  tempting  to  suppose  that  these  different  creatures  follow 
the  path  of  a  common  ancestor  while  they  are  living  the  free- 
swimming  life  of  that  ancestor,  and  then  sharply  diverge  to  reach 
their  different  goals.  But  we  have  to  remember  that  a  meta- 
morphosis cannot  be  a  primitive  mode  of  development,  and  that 
where  it  exists  a  long  history  has  been  blotted  out.  And  we  have 
also  to  remember  that  the  resemblances  of  the  larvae  are  in  plain 
relation  to  similar  habits,  and  may  have  no  ancestral  meaning. 

The  great  class  of  Crustacea  includes  crabs,  lobsters,  crayfish, 
prawns,  shrimps,  sandhoppers,  woodlice,  barnacles  and  water -fleas 
and  many  less  well  known  creatures.  Like  insects  and  spiders, 
they  have  jointed  limbs,  arranged  in  pairs,  and  the  body  is  covered 
by  a  hard  external  case  to  the  inside  of  which  the  muscles  are 
attached,  and  which  is  usually  known  as  the  shell.  Most  of  them 
live  in  or  near  water,  and  the  terrestrial  forms  show  plain  traces  of 
aquatic  ancestry.  The  young  of  many  of  them,  especially  those 
that  live  in  fresh  water  or  on  land,  pass  through  their  period  of 
youth  in  fashions  that  are  quite  clearly  direct  adaptations  to  the 
special  circumstances  of  their  lives.  The  marine  crustaceans 
usually  lay  small  eggs  which  hatch  out  into  larvae  extremely  unlike 
their  parents,  although  the  external  shell  and  jointed  limbs  show 
plainly  that  they  are  crustaceans  and  betray  no  resemblance  with 
any  other  group  of  the  animal  kingdom.  The  larvae  swim  about, 
feed,  and  after  a  few  days  or  weeks  the  hard  shell  becomes  too  tight 
for  the  plump  body,  and  splits  open,  setting  free  the  animal,  clad 
in  a  soft  skin  and  at  once  swelling  to  a  size  rather  larger  than  that  of 
the  case  from  which  it  emerged.  Very  quickly  the  skin  hardens 
to  form  a  new  shell,  and  this  second  larva  is  not  exactly  like  the 
first  larva,  but  rather  more  complicated,  and  more  near  the  adult 
form.  The  same  sequence  is  followed  again,  and  may  be  repeated 


28  CHILDHOOD  OF  ANIMALS 

in  many  successive  moults,  until  a  moult  comes  after  which  the  young 
creature  has  the  final  form  of  its  species.    The  seas  teem  with 
these  larvae,  especially  in  summer,  when  the  water  is  warm.    They 
feed  on  one  another,  and  on  the  small  floating  plants  which,  like  the 
green  herbage  of  the  land,  are  the  ultimate  food-supply  of  the  living 
world,  and  they  themselves  are  preyed  upon  by  hosts  of  fishes. 
The  larvae  appear  in  many  curious  shapes,  but  in  those  cases  where 
there  are  the  greatest  number  of  successive  larvae  and  moults  be- 
tween the  egg  and  the  adult,  the  series  shows  a  rough  correspondence 
with  what  may  be  supposed  to  be  the  ancestral  history  of  the 
crustacean  in  question.      In  those  with  fewer  larvae  the  jumps  are 
bigger,  some  stages  being  suppressed,  whilst  the  regularity  of  the 
sequence  is  often  confused  by  the  premature  appearance  of  some  of 
the  organs  or  appendages,  and  the  retarded  appearance  of  others. 
The  starting-point  in  those  larvae  in  which  the  series  is  most  com- 
plete, and  which  appears  in  more  different  kinds  of  Crustacea  than 
any  other  larva,  is  what    is  called  the  nauplius.      The  nauplius 
(Fig.  14)   has   an  oval  body,  not  divided  into  rings  or  segments, 
with  a  large  median  eye  on  the  dorsal  surface  of  the  anterior  end. 
It  has  a  mouth  on  the  ventral  surface,  under  the  eye,  protected  by 
a  kind  of  membranous  upper  lip,  and  it  has  three  pairs  of  swimming 
appendages,  the  front  pair  of  which  occupy  the  position  of,  and 
correspond  with,  the  antennules  or  front  pair  of  feelers  of  the  lobster 
or  crayfish.    Those  of  the  second  pair  are  forked,  and  usually  have 
hooks  at  their  bases  which  lie  on  either  side  of  the  mouth  and  serve  as 
jaws.    They  correspond  with  the  antennae,  or  second  pair  of  feelers 
of  the  adults.     The  third  pair,  situated  a  little  farther  back,  are  also 
forked  and  correspond  with  the  mandibles  or  true  jaws  of  the  adults. 
In  prawns  (of  the  genus  Penaus)  the  nauplius  larva  is  succeeded 
by  a  larger  larva  called  the  metanauplius  (Fig.  14),  in  which  the 
swimming  parts  of  the  third  pair  of  appendages  are  smaller  whilst 
a  strong  jaw  portion  is  developed.     Behind,  there  are  the  beginnings 
of  four  other  pairs  of  limbs.    Next  comes  a  protozoea  larva  with 
the  same  seven  pairs  of  appendages,  a  carapace  or  shell  beginning  to 
spread  over  the  dorsal  surface  of  the  anterior  part  of  the  body, 
and  a  long,  forked,  but  unjointed  abdomen.     The  third  pair  of 
appendages  has  ceased   to  be  of  use  in   swimming,  and  is  wholly 
transformed  to  the  pair  of  jaws  or  mandibles.    The  paired  eyes  begin 
to  show  through  the  carapace.      For  several  successive  moults 
there  is  not  much  change  in  shape,  but.  the  eyes  push  through  the 
carapace,  and  the  abdomen  becomes  longer,  is  divided  into  joints, 


LARV.E  AND  METAMORPHOSES 


29 


FIG.  14.  Larvae  of  the  Crustacean  Penceus.  Upper  left-hand  figure, 
Nauplius;  upper  right-hand,  Protozoea.  Lower  left-hand  figure,  Zoea; 
lower  right-hand,  Schizopod  stage.  (After  F.  MULLER  and  CLAUS  ; 
much  enlarged.) 

and  shows  the  buds  of  more  pairs  of  limbs.  In  the  next  stage,  which 
is  called  the  Zoea  (Fig.  14),  the  paired  eyes  have  become  movable, 
being  mounted  on  long  stalks,  the  carapace  projects  in  front  as 


30  CHILDHOOD  OF  ANIMALS 

a  long  spine,  and  the  abdomen  is  very  long,  almost  devoid  of  appen- 
dages along  the  greater  part  of  its  length,  but  with  a  large  pair  on  the 
second  last  segment.  After  several  moults,  with  further  slight 
changes,  a  larva  appears  which  is  called  the  mysis  stage  or  schizopod 
stage  (Fig.  14),  from  its  resemblance  with  the  adult  form  of  a  lower 
kind  of  crustacean.  In  this  stage  the  projecting  spine  of  the  carapace 
is  very  long,  the  abdomen  has  a  complete  set  of  swimming  limbs, 
those  of  the  last  pair  being  large  and  forming  with  the  last  segment 
itself  a  swimming  tail-fan  like  that  of  an  adult  lobster  or  prawn. 
In  a  further  set  of  moults  the  complete  shape  of  the  adult  is 
acquired  by  the  body  and  limbs. 

In  most  of  the  higher  Crustacea,  the  number  of  moults  is  smaller, 
and  there  are  bigger  jumps  between  the  successive  types  of  larvae. 
The  earliest  larva  of  crabs  is  a  fully  formed  zoea,  which  is  dis- 
tinguished from  the  zoea  of  other  Crustacea  by  a  very  long  spine 
on  the  carapace,  but,  almost  immediately  after  hatching,  a  thin 
cuticle  is  cast  off,  and  this  differs  from  the  zoea  itself  and  appears  to 
be  the  last  remnant  of  one  of  the  suppressed  larval  stages.  Next 
come  a  set  of  larvae  called  the  megalopa  stages;  which  quickly  acquire 
the  appendages  and  general  form  of  the  adult  crab,  but  which  have 
a  long  extended  abdomen.  After  the  moult  from  which  an  animal 
that  can  first  be  called  a  crab  appears,  the  abdomen  is  tucked  up 
under  the  body  as  a  rudimentary  triangular  flap. 

Study  of  the  larval  development  of  a  very  large  number  of  marine 
crustaceans,  of  which  I  have  chosen  only  a  few  examples,  would 
seem  to  give  a  clear  picture  of  the  general  course  of  events.  Because 
they  have  a  hard,  shell-like  skin,  young  crustaceans  cannot  grow 
larger  in  the  usual  way  of  soft -skinned  animals.  They  must  grow 
in  size  by  a  succession  of  moults.  This  makes  it  impossible  for  the 
youthful  period  to  be  a  time  of  slow  and  continuous  change,  from 
the  first  larva  to  the  adult.  The  changes  must  take  place  by  jumps. 
Where  there  are  a  great  many  different  successive  larvae,  each  a 
little  more  complicated  than  its  predecessor,  we  seem  to  see  the 
simplest  method  of  arriving  at  the  result,  and  the  greatest  probability 
that  the  larval  history  is  at  least  partly  a  repetition  of  the  ancestral 
history.  And  the  facts  that  many  of  these  larvae  are  closely  alike, 
although  they  belong  to  different  groups  of  Crustacea,  and  that  the 
larvae  of  the  higher  groups  not  infrequently  resemble  the  adults  of 
the  lower  groups,  greatly  increase  the  probability  of  this  ancestral 
interpretation  being  correct. 

Insects,  like  Crustacea,  are  Arthropods  with  a  hard  external 


LARVAE  AND  METAMORPHOSES  31 

skeleton  and  jointed  limbs,  and  in  their  development  show  a  series 
of  moults.  No  life -history  in  the  animal  kingdom  is  more  surprising 
than  that  of  a  fly  like  the  blow-fly.  The  eggs  are  laid  on  animal 
matter,  and  the  flies,  no  doubt  attracted  by  the  smell,  prefer  matter 
that  is  just  beginning  to  soften  with  putrefaction.  The  eggs  hatch 
out  into  the  little  brown -headed  white  maggots  known  as  gentles 
(Fig.  15).  They  have  a  pair  of  strong  jaws  with  which  they  devour 
the  animal  matter  in  which  they  are  living,  a  segmented  body  clad 
in  a  tough  leathery  skin,  and  no  trace  of  limbs.  They  moult  two 
or  three  times  without  changing  their  shape,  but  growing  larger, 
and  soon  after  the  last  moult,  contract  into  a  quiescent  oval  body, 
covered  with  the  skin  of  the  larva  which  has  become  dry  and  brown. 
After  some  days  passed  in  this  f^^^-sp^^ 
motionless  state,  the  brown  skin  ;,  ;  >;  ?^-»^ 

splits,  and  the  fully  formed  adult   |    .>:,.". 
fly  emerges,  and  in  a  few  minutes    V  >         -  - 

is  winging  its  way  through  the  air,  __  .^ ,^™^^ 

as  unlike  the  worm-shaped  larva  ::^-      ,  ^ 

as  any  creature  could  be.     With  ) 

the    exception     of    the    nervous  ^M^  -K^ 

system  and  parts  of  some  other  _ 

J  .  .£     ,  ,     n         ,    FIG.   15.     Larva  (upper    figure)    and 

organs,  it  seems  as  if  the  whole  of  pupa  (lower  figure)  of  Blow-fly, 
the  organs  inside  the  hardened  skin  enlarged)™*  ""*  PACKARD; 
of  the  larva  melted  down  and 

became  rearranged  to  form  the  very  different  organs  of  the  adult. 
Patient  and  extremely  difficult  dissections,  however,  have  shown 
that  there  is  an  intelligible  order  in  this  transformation.  Some 
time  before  the  fly  emerges  it  is  surrounded  by  two  delicate  and 
transparent  skins.  The  inner  of  these,  if  we  could  imagine  it  taken 
out  whole,  plumped  up  with  air,  and  dried,  would  have  the  appear- 
ance of  a  fly  with  a  head  bearing  antennae,  eyes  and  mouth-organs, 
a  body  with  small  wings  and  six-jointed  legs,  and  a  pointed  abdomen, 
but  with  all  these  organs  and  parts,  and  especially  the  wings,  not 
quite  like  those  of  a  modern  fly,  but  rather  simpler.  This  skin  is  the 
pale  ghost  of  a  former  metamorphosis,  of  a  true  moult  once  passed 
through  by  the  ancestors  of  the  flies,  but  now  on  its  way  to  be 
suppressed.  The  outer  thin  skin  is  the  similar  remains  of  a  still 
earlier  moult,  and  its  structure,  although  still  fly -like,  is  less  fly -like 
than  the  inner  skin. 

The  development  of  a  moth  such  as  the  well-known  privet  hawk- 
moth  carries  the  story  a  little  further.    The  eggs  are  laid  on  the 


32  CHILDHOOD  OF  ANIMALS 

privet  and  hatch  into  caterpillars  which  feed  on  the  leaves.  The 
caterpillar  (Fig.  16)  has  a  head  and  a  jointed  worm-like  body. 
The  head  has  six  simple  eyes,  a  pair  of  three -jointed  very  small 
antennae,  and  biting  jaws.  The  first  three  segments  of  the  body 
carry  each  a  pair  of  five -jointed  clawed  legs,  corresponding  with  the 
legs  of  the  adult  insect.  Four  of  the  other  ten  segments  carry  each 
pair  of  larval  legs,  called  prolegs,  and  not  represented  in  the  adult, 
but  entirely  for  the  purposes  of  the  larva.  The  caterpillar  feeds  and 
grows,  and  moults  three  or  four  times.  Before  the  last  moult, 
it  becomes  restless  and  wanders  about,  ceasing  to  feed.  It  is  ready 

for  pupation,  and  is 
seeking  a  suitable 
place.  Some  cater- 
pillars suspend  them- 
selves to  the  branch 
of  a  tree  or  to  a  pro- 
jecting point  in  a  dry 
crevice.  Others  spin 
a  cocoon  of  silk. 
Others,  such  as  the 
privet  hawk  -  moth 
caterpillar,  descend  to 
the  ground  and  scoop 
out  a  dry  burrow. 

FIG.  1 6.   Caterpillar  (upper  figure)  and  Chrysalid  (lower  There  the  last    moult 
figure)  of  Privet  Hawk-moth.     (Slightly  reduced.)     takes   place,    and    the 

pupa  or  chrysalid  (Fig.  16)  emerges,  and  very  quickly  becomes 
hard  and  brown.  If  it  be  examined  closely,  however,  it  can  be  seen 
to  resemble  a  moth  more  than  a  caterpillar.  It  shows  the  shape  of  the 
head,  body  and  abdomen  of  the  moth  and  carries  the  appendages  of 
a  moth,  not  of  a  caterpillar,  and  is  provided  with  short,  folded 
wings.  These  are  at  first  free,  but  soon,  before  the  skin  has  become 
dry  and  brown,  are  glued  down  with  a  sticky  secretion.  The  pupa 
is  able  to  wriggle,  but  remains  practically  motionless  while  the 
transformation  to  the  adult  is  taking  place.  In  the  course  of  this 
there  is  a  suppressed  moult,  shown  by  the  presence  of  a  very  thin 
skin  covering  the  body  of  the  moth  inside  the  pupa-case,  like  one  of 
the  two  skins  in  the  blow-fly,  and  like  these  representing  an  almost 
forgotten  moult.  When  the  moth  emerges,  it  is  ready  to  fly  as  soon 
as  its  wings  have  expanded  and  dried,  and  it  is  extremely  unlike  the 
caterpillar.  But  the  gap  is  not  so  great  as  in  the  blow-fly.  In  the 


LARV.E  AND  METAMORPHOSES 


33 


first  place,  the  pupa  or  chrysalis  is  much  more  like  the  moth  than  the 
puparium  or  skin  of  the  blow-fly  larva  is  like  the  blow-fly.  In 
the  second  place,  the  caterpillar,  with  its  antennae,  eyes  and  three 
pairs  of  jointed,  walking  legs,  is  much  more  like  an  insect  than  is  the 
legless  maggot. 

Some  small  insects  of  which  the  oil-beetle  is  a  good  example 
expand  the  contracted  history  of  the  higher  insects  still  more. 
The  eggs  hatch  out  into  active  larvae  showing  a  head  bearing  eyes 
and  antennae,  a  body  of  three  joints  each  bearing  a  pair  of  fully 
formed  clawed  legs,  and  a  jointed  abdomen  with  a  pair  of  long 
bristle -like  projections  behind. 
These  larvae  (Fig.  17),  although 
they  have  no  wings,  are  insect - 
like  in  form,  and  are  called 
Campodeiform  larvae ;  no  one 
observing  them  for  the  first 
time  could  doubt  but  that 
they  are  insects  of  a  primitive 
kind ;  moreover  they  are  ex- 
tremely like  the  members  of 
the  lowest  group  of  existing 
insects,  the  Apt  era  or  wingless 
insects,  of  which  the  silver-fish 
and  the  bristle-tail  are  well- 
known  examples.  These  larvae 
run  about,  climb  up  flowers, 
and  have  the  instinct  of  clinging  to  any  hairy  object.  If  a  bee 
comes  their  way,  on  a  visit  to  a  flower,  they  at  once  seize  hold 
of  its  hairy  body.  If  it  is  an  unsuitable  bee,  they  perish,  but 
if  it  is  the  right  kind  for  their  purpose  (Anthophora  or  Andrena) 
they  are  carried  to  the  nest  of  their  host,  and  when  the  bee  lays 
an  egg  in  a  cell,  the  larva  slips  off  and  climbs  on  the  egg  which 
is  floating  in  the  honey.  The  larva  eats  the  contents  of  the  egg 
and  then  moults.  The  second  larva  which  comes  out  is  much  less 
like  an  insect  than  the  first ;  it  is  a  fleshy  grub,  not  well  divided  into 
head,  body,  and  abdomen,  and  with  three  short  pairs  of  legs.  It  is 
intermediate  between  the  degenerate  maggot  of  the  blow-fly  and 
the  caterpillar  of  the  moth.  This  grub  floats  in  the  honey  and 
devours  it  and  then  moults  once  more,  a  still  more  degenerate  motion- 
less form  appearing,  with  no  movable  appendage  on  the  head  and 
with  only  six  stumps  in  the  place  of  the  legs.  This  in  its  turn 

c.A.  c 


pa 

Beetle.  Figure  to  the  left,  Campodei- 
form larva  ;  middle  figure,  maggot- 
like  larva ;  figure  to  right,  pupa.  (After 
PACKARD  ;  much  enlarged.) 


34  CHILDHOOD  OF  ANIMALS 

moults  and  changes  to  a  pupa  rather  like  the  adult  in  form,  with 
the  appendages  and  rudimentary  wings  glued  down  to  the  body. 
After  a  resting  stage  this  pupa  opens  and  the  adult  insect  emerges. 

The  eggs  of  other  beetles  may  hatch  out  either  as  campodeiform 
larvae,  or  as  maggot -like  larvae,  which,  after  moulting,  produce 
pupae  with  rudimentary  wings.  The  eggs  of  many  other  insects, 
such  as  cockroaches  and  earwigs,  hatch  out  as  campodeiform  larvae, 
and  then  by  a  series  of  moults  slowly  acquire  the  adult  form  without 
any  true  metamorphosis. 

Finally  there  are  many  insects,  such  as  the  locusts,  in  which  the 
earliest  stages  have  been  suppressed  and  there  is  no  sudden  meta- 
morphosis, but  the  period  of  youth  is  occupied  by  a  series  of  moults 
(Fig.  18),  in  which  the  successive  larvae  slowly  assume  the 
characters  of  the  adult,  the  wings  gradually  growing  longer. 

I  do  not  wish  to  suggest  that  the  examples  I  have  chosen  represent 
actual  stages  in  the  evolution  of  insects.  They  have  been  selected 
from  insects  that  are  by  no  means  closely  related,  and  they  do  no 
more  than  give  an  idea  how  the  extremely  different  modes  in  which 
modern  insects  develop  show  a  trace  here  and  a  trace  there  of 
different  parts  of  a  common  ancestral  history,  some  parts  of  which 
have  been  blurred  and  condensed  in  some  insects,  other  parts  in 
others.  The  delicate  and  transparent  pupal  skins  surrounding  the 
fly  inside  its  puparium,  with  their  rudimentary  wings,  and  the  pupal 
cases  themselves  of  moths  and  oil -beetles  with  their  rudimentary 
wings,  plainly  represent  the  active  later  larval  stages  of  the  locust. 
The  campodeiform  larvae  of  the  oil -beetle  and  of  many  other  beetles, 
cockroaches  and  earwigs  represent  the  primitive  insect,  and  may 
pass  by  a  series  of  moults  into  the  adult,  or  these  later  stages  may 
have  been  condensed  to  a  sudden  metamorphosis.  The  caterpillar- 
like  larva  is  a  rather  degenerate  modification  of  the  Campodea 
larva,  and  the  maggot -like  larvae  of  many  beetles  and  the  legless 
larvae  of  flies  are  still  more  degenerate  interpolations  in  the  life- 
history,  fitting  the  special  conditions  in  which  these  larvae  live. 

The  stories  of  the  youthful  period  in  the  crustaceans  and  insects 
are,  to  a  certain  extent,  alike.  The  hard  nature  of  the  skin  has  led 
to  a  replacement  of  the  more  usual  method  of  continuous  growth, 
by  growth  in  little  jumps,  there  being  a  moult  at  each  jump.  In  both 
there  are  many  animals  in  which  these  successive  moults  separate  a 
set  of  larvae  which  are  becoming  more  and  more  like  the  adult  by 
slow  stages.  In  both  the  more  continuous  sets  of  larvae  seem  to  be  at 
least  a  partial  repetition  of  the  ancestral  history,  but  in  both  the 


FIG.  1 8.  Development  of  a  Locust.  The  upper  figure,  showing  the 
youngest  stage,  is  considerably  more  enlarged  than  the  others,  which 
are  all  magnified  to  the  same  scale.  (AJter  PACKARD.) 


36  CHILDHOOD  OF  ANIMALS 

larvae  are  modified  in  many  ways  to  suit  the  needs  of  their  own  life, 
and  it  is  a  difficult  judgment  to  decide  in  any  case  how  much  of 
the  character  of  a  larva  is  adaptive  and  how  much  ancestral.  In 
both  groups  the  continuous  series  may  be  interrupted  at  any  point, 
by  the  obliteration  or  telescoping  of  some  of  the  stages,  with  the 
result  that  occasionally  a  moult  is  preceded  by  a  resting  phase  in 
which  the  larva  is  more  or  less  torpid  and  motionless,  and  when  the 
form  that  emerges  from  the  moult  is  widely  different  from  the 
preceding  form.  Such  bigger  jumps  give  rise  to  the  familiar 
metamorphoses,  and  they  are  most  frequent  and  most  decided  when 
they  are  associated  with  a  change  in  the  habits  of  the  creatures 
before  and  after  the  metamorphic  moult. 

There  is  one  striking  difference  between  the  two  groups.  Amongst 
insects  the  campodeiform  larva,  which  is  certainly  the  most  primi- 
tive, represents  the  most  primitive  group  of  living  insects,  and,  more- 
over, helps  to  link  insects  with  another  group,  the  group  of  centipede- 
like  animals.  In  Crustacea,  the  nauplius  larva,  which  is  certainly 
the  most  primitive,  does  not  represent  any  living  group  of  Crus- 
tacea and  does  not  link  the  Crustacea  directly  with  any  other  group. 
Unlike  the  campodea  larva  which,  but  for  the  absence  of  reproductive 
organs,  has  the  appearance  and  characters  of  an  adult  animal,  the 
nauplius  larva  is  plainly  an  immature  creature. 

When  Darwin  first  convinced  naturalists  that  the  living  world  as 
we  see  it  now  had  come  into  existence  by  a  process  of  evolution,  the 
resemblance  amongst  the  larvae  of  different  animals,  the  resemblances 
of  the  larvae  of  one  set  of  animals  with  the  adults  of  lower  animals, 
and  the  parallel  between  the  larval  development  and  the  possible 
ancestral  history  were  thought  to  provide  almost  clear  proof  of  the 
fact  of  evolution  and  to  show  the  actual  path  of  evolution.  But 
although  increase  of  knowledge  has  strengthened  the  general  case 
for  evolution  to  such  an  extent  that  a  reasonable  naturalist  can  no 
longer  doubt  it,  we  are  getting  more  wary  as  to  particular  cases. 
The  struggle  for  existence  amongst  larvae  is  extremely  severe  ;  of 
the  multitudes  that  are  hatched,  only  a  few  reach  adult  life,  and 
then  only  after  having  escaped  almost  incredible  dangers.  And  so 
larvae  have  been  shaped  and  moulded,  coloured  and  armed  in  a 
multitude  of  ways  that  fit  them  to  the  conditions  in  which  they 
live.  And  in  this  process  they  must  have  lost  much  of  their  in- 
herited ancestral  characters  and  must  have  acquired  many  delusive 
resemblances. 


CHAPTER  III 
THE  DURATION  OF  YOUTH  IN  MAMMALS 

I  ENTERED  the  University  of  Aberdeen  a  few  weeks  before  I  was 
sixteen  years  old,  and  it  pleased  me  to  find  that  most  of  those  in 
my  class  were  several  years  older.  Kind  relatives  endeavoured  to 
chasten  my  pride  by  telling  me  of  various  distinguished  professors 
who  had  joined  when  they  were  only  twelve  or  thirteen  years 
of  age.  As  I  had  not  then  learned  the  folly  of  meeting  the  reproofs 
of  my  elders  with  rational  arguments,  I  replied  by  saying  that  in 
those  prehistoric  days  University  education  was  on  a  lower  grade, 
and  that  students  matriculated  before  they  had  begun  to  learn  Greek 
or  Mathematics.  And  I  have  no  doubt  but  that  to-day  many  of 
the  first  year's  courses  at  the  Universities  begin  where  we  left  off. 
So  also  it  is  with  most  of  the  pursuits  of  life.  In  business,  in  handi- 
crafts, and  in  professions  the  period  of  education  (in  the  common 
sense  of  the  word)  is  growing  longer,  and  youths  are  older  when  they 
emerge  from  the  pupillary  stage.  But  although  they  are  older 
in  years,  I  do  not  think  that  they  are  physically  older.  They  retain 
the  flexibility,  the  high  spirits,  the  sense  of  irresponsibility,  and 
many  of  the  purely  physical  characters  of  youth,  such  as  practical 
indifference  to  the  other  sex,  for  a  longer  time.  In  the  civilised 
races  and  especially  in  the  more  intellectual  classes,  the  some- 
what indefinite  transition  from  youth  to  manhood  does  not 
occur  till  after  the  age  of  twenty.  There  is  a  parallel  change  in  the 
case  of  women.  Our  grandmothers  were  married  and  became  the 
responsible  heads  of  establishments  at  ages  of  thirteen,  fourteen,  or 
fifteen  years,  an  arrangement  which  would  be  regarded  as  scandalous 
to-day.  The  transition  from  boyhood  to  manhood  or  from  girlhood 
to  womanhood,  using  these  somewhat  indefinite  terms  in  the  widest 
sense,  comes  later.  No  doubt  there  are  racial  differences  as  well 
as  differences  of  civilisation  and  of  class,  and  in  the  case  of  Europe 
the  long-headed,  dark-skinned  peoples  along  the  northern  shore  of 
the  Mediterranean,  although  they  may  be  equally  civilised,  mature 
at  rather  earlier  ages  than  the  round-headed  peoples  of  Central 

37 


38  CHILDHOOD  OF  ANIMALS 

Europe  or  the  long-headed,  fair-skinned  natives  of  the  North.  But 
amongst  these,  too,  the  period  of  youth  is  stretching  out,  and  we 
may  fairly  say  that  youth  in  civilised  man  lasts  for  at  least  twenty 
years.  Exact  observations  on  the  lower  races  of  man  relating  to 
this  point  are  not  very  numerous,  but  there  is  a  general  agreement 
amongst  those  with  knowledge  that  both  males  and  females  of  the 
lower  races  mature  much  earlier.  Probably  it  would  be  fair  to  set 
down  from  twelve  to  fifteen  years  as  the  duration  of  youth  in  most 
of  the  lower  human  races. 

The  animals  that  approach  man  most  closely  in  size  and  structure 
are  the  anthropoid  or  man -like  apes.  Gorillas,  which  live  in  the 
tropical  forests  of  West  Africa,  are  larger  than  human  beings.  They 
are  much  more  bulky,  and  their  legs  and  arms  are  longer.  A  full- 
grown  male,  if  it  stood  perfectly  upright,  would  be  considerably 
more  than  six  feet  in  height.  Chimpanzees,  which  live  in  the  same 
parts  of  Africa  as  the  gorilla,  but  also  extend  much  further  to  the  east, 
have  long  arms  and  legs,  but  are  not  so  large  and  heavy,  and  even 
if  fully  upright  would  seldom  reach  five  feet  in  height.  Orang-utans, 
which  are  natives  of  Borneo  and  Sumatra,  have  relatively  longer 
legs  and  arms  than  the  others,  but  are  even  less  upright.  The 
largest  orang  is  not  more  than  just  over  five  feet  in  height,  but  the 
great  bulk  of  their  bodies  exceeds  that  of  ordinary  human  beings 
and  is  intermediate  between  the  bulks  of  the  gorilla  and  chimpanzee. 
The  gibbons,  of  which  there  are  many  species,  ranging  over  a  large 
part  of  tropical  Asia,  are  much  more  erect  in  posture  than  any  of  the 
other  anthropoid  apes,  and  their  arms  and  legs  are  extremely  long. 
Their  bodies  are  slight,  and  the  largest  specimen  of  the  largest  species 
probably  is  not  more  than  four  feet  in  height,  and  is  therefore 
smaller  and  lighter  than  a  human  being. 

The  gorilla,  the  chimpanzee  and  the  orang  carefully  avoid  the 
neighbourhood  of  man,  and  although  gibbons  are  less  shy,  their 
life,  passed  chiefly  in  the  tall  trees  of  forests,  makes  careful  and 
prolonged  observation  difficult.  We  have  therefore  no  exact 
knowledge  of  their  breeding  habits,  or  of  the  duration  of  their  youth 
in  the  wild  condition.  They  are  notoriously  difficult  to  keep  alive 
in  captivity.  One  gorilla  lived  for  several  years  in  the  Zoological 
Gardens  at  Frankfurt ;  all  the  great  Zoological  Gardens  have  made 
many  attempts,  but  these  apes  seldom  live  for  more  than  a  few  weeks 
after  their  arrival.  Orangs  were  long  supposed  to  be  equally  delicate, 
but  more  recently  there  has  been  greater  success  with  them,  and  at 
the  present  time  there  is  alive  in  the  London  Zoological  Gardens  a 


DURATION  OF  YOUTH  IN  MAMMALS          39 

fine  male  which  has  been  there  for  seven  years.  Chimpanzees  are 
obtained  in  much  larger  numbers  and,  although  they  are  very  delicate, 
individuals  have  frequently  lived  in  captivity  for  a  number  of  years. 
The  "  record  "  is  held  by  the  London  Society,  and  in  the  Gardens  at 
Regent's  Park  there  is  a  chimpanzee  which  has  lived  for  fourteen 
years.  Unfortunately  it  is  a  dwarf,  either  congenitally  or  as  the 
result  of  the  artificial  conditions  in  which  it  has  lived.  Individual 
gibbons  have  lived  for  several  years,  but  in  most  cases  they  too 
succumb  very  quickly. 

I  do  not  know  if  anthropoid  apes  would  be  likely  to  breed  in 
captivity,  but  as  most  of  them  are  taken  when  they  are  very  young 
and  do  not  live  to  maturity,  there  has  been  no  opportunity,  and  I 
do  not  know  of  any  case  of  a  birth  having  taken  place  in  menageries. 
Unfortunately,  also,  it  is  certain  that  little  reliance  can  be  placed 
on  the  rate  of  growth  of  the  apes  in  captivity.  Better  accommo- 
dation, less  coddling  and  more  reasonable  food  are  certainly  im- 
proving the  general  health  of  captive  apes,  and  probably  their  rate 
of  growth  is  often  more  natural  than  it  used  to  be.  But  we  have 
still  to  rely  chiefly  on  comparisons  with  human  beings,  based  on  size, 
the  appearance  of  puberty,  the  closing  of  the  skull  bones,  changes 
in  the  teeth  and  so  forth,  and  there  is  no  reason  to  be  certain  that 
such  comparisons  are  not  misleading.  It  is  generally  assumed, 
however,  that  the  duration  of  youth  in  anthropoid  apes  is  from 
eight  to  twelve  years,  and  the  estimate  is  probably  not  very  far 
wrong. 

The  lower  monkeys  range  in  size  from  the  large  baboons,  which 
exceed  gibbons  in  bulk  and  weight,  to  tiny  monkeys  like  marmosets 
which  may  be  no  larger  than  a  small  squirrel.  Although  on  the  whole 
they  are  also  rather  delicate  in  captivity,  so  many  have  been  kept 
by  private  persons  or  in  public  institutions  that  it  is  not  surprising 
that  there  have  been  frequent  successes.  Many  different  species 
have  been  bred  in  captivity  and  reared  to  maturity.  The  larger 
monkeys,  like  baboons  and  mandrills,  take  from  eight  to  twelve 
years  to  grow  up.  Middle-sized  monkeys,  like  common  Asiatic 
macaques,  take  from  three  to  five  or  six  years.  A  pair  of  Japanese 
apes  in  the  London  Zoological  Gardens  were  the  parents  of  a  baby 
born  in  January  1906  ;  in  the  beginning  of  1912  the  young  one  was 
nearly,  but  not  quite,  fully  grown.  It  lived  with  its  parents  in  an 
enclosure  consisting  of  an  open-air  cage  about  ten  feet  by  ten  in 
area,  provided  with  branches  on  which  to  climb,  and  with  an  un- 
heated,  covered  sleeping-den.  Although  the  conditions  were  better 


40  CHILDHOOD  OF  ANIMALS 

than  those  often  given  to  monkeys  in  captivity,  I  am  inclined  to  think 
that  they  were  not  varied  enough,  nor  exciting  enough  for  the 
normal  rate  of  growth.  The  small  American  monkeys,  such  as  mar- 
mosets, become  full  grown  in  from  two  to  three  years. 

The  length  of  the  period  of  youth  thus  becomes  shorter  and 
shorter  as  we  descend  from  the  highest  human  types  to  the  lowest 
monkeys,  and  is  parallel  with  some  other  qualities  of  this  group  of 
animals.  The  potential  longevity,  the  age  to  which  an  animal  can 
attain  under  the  most  favourable  conditions,  is  greatest  in  the  higher 
races  of  man,  where  it  may  be  a  century,  seldom  exceeds  fifty  or 
sixty  years  in  the  lower  races  of  man,  and,  so  far  as  the  somewhat 
scanty  evidence  at  our  disposal  goes,  decreases  as  we  pass  down  the 
scale  of  monkeys  from  the  man -like  apes  to  the  simplest  little 
monkeys.  It  cannot  be  said,  however,  that  there  is  any  definite 
proportion  between  the  length  of  youth  and  the  length  of  the  whole 
life,  in  the  fashion  that  the  Greeks  supposed  the  height  of  the  head 
to  be  a  definite  proportion  of  the  total  height.  The  span  of  a  com- 
plete life  is  not  divided  according  to  any  ideal  rule  or  law  into  so 
many  parts  for  helpless  infancy,  so  many  for  aspiring  youth,  and 
so  many  for  maturity.  Each  portion  varies  with  the  particular  needs 
of  the  particular  species,  and  no  more  is  to  be  expected  than  that 
the  mode  of  division  should  be  rather  more  alike  amongst  species 
that  are  nearly  related,  and  rather  less  alike  amongst  species  that 
are  far  separate. 

There  is  also  a  rough  correspondence  between  the  duration  of  youth 
and  the  size  of  the  creatures  in  the  man-monkey  group.  A  full-grown 
male  gorilla,  it  is  true,  is  larger,  although  not  taller,  than  a  finely 
built  man,  but  the  human  race  as  a  whole  consists  of  larger  and  finer 
animals  than  the  anthropoid  apes,  whilst  these  in  their  turn  exceed 
the  baboons,  which  exceed  the  ordinary  monkeys  of  India  and 
Africa,  and  so  on  down  to  the  tiny  marmosets.  It  is  tempting 
to  suppose  that  it  must  take  longer  to  grow  into  a  big  animal  than 
into  a  little  animal.  This  also  is  true  only  when  nearly  related 
creatures  are  compared.  Mere  increase  of  bulk  tells  us  little.  A 
mushroom  grows  much  more  quickly  than  a  daisy,  a  gooseberry 
and  a  huge  vegetable  marrow  take  nearly  the  same  time  to  swell 
out.  A  human  child  takes  nearly  two  hundred  days  to  double  its 
weight  at  birth,  whilst  new-born  mice  quadruple  their  weight  in 
twenty -four  hours.  The  nature  of  the  organism,  the  complexity 
of  its  structure  and  the  particular  conditions  under  which 
it  lives  must  all  be  taken  into  account,  and  are  of  more 


DURATION  OF  YOUTH  IN  MAMMALS          41 

importance  than  actual  size.  Within  each  group  of  nearly  related 
animals,  the  duration  of  youth  is  in  rough  agreement  with  the 
possible  span  of  the  whole  life,  and  with  the  relative  size  to  which 
the  members  of  the  particular  species  attain.  But  the  agreement 
is  not  exact.  There  are  very  many  instances  in  the  animal 
kingdom,  and  I  shall  mention  some  of  them,  in  which  there  is  no 
reasonable  proportion  between  size  or  the  potential  longevity,  and 
the  duration  of  youth. 

The  descending  scale  from  man  to  the  lowest  monkeys,  which  is 
fairly  plain  in  the  case  of  size  and  of  longevity,  is  quite  certain  if  we 
take  into  consideration  the  complete  structure  and  especially  the 
mental  capacities  of  the  members  of  the  series.  When  animals 
belonging  to  different  groups  are  compared,  it  is  not  very  easy 
ito  say  which  is  to  be  regarded  as  higher  and  which  lower.  Most 
persons  would  agree  that  the  cats,  including  the  large  cats  like  the 
lion  and  the  tiger  and  the  small  cats  like  the  domestic  cat,  are  the 
highest  of  the  carnivorous  animals.  But  is  a  cat  a  higher  or  lower 
animal  than  an  elephant  ?  Inside  a  group,  however,  comparison  is 
easier,  and  especially  if  we  take  into  consideration  the  size  and 
structure  of  the  brain,  there  is  no  doubt  but  that  man  stands 
supremely  at  the  head  of  his  tribe  and  that  there  is  a  rapid  descent 
from  him  to  the  lowest  monkeys.  The  most  certain  and  the  most 
important  feature  about  the  differences  in  the  duration  of  youth, 
and  what  is  specially  clear  in  the  case  of  man  and  his  relations,  is 
that  the  length  of  the  period  of  youth  varies  with  the  degree  of 
intelligence  to  which  the  adult  can  attain.  Civilised  man  is  the 
most  intelligent  and  takes  longest  to  grow  up  ;  the  smallest  monkeys 
are  the  least  intelligent  and  hurry  over  the  period  of  youth  most 
quickly. 

As  a  good  many  of  the  Carnivora  have  bred  in  captivity,  we  have 
a  fairly  extensive  knowledge  of  the  duration  of  their  youth,  although 
it  is  to  be  remembered  that  the  new  conditions  to  which  they  are 
subjected  may  have  an  effect  on  their  rates  of  growth,  probably 
accelerating  it.  Lions  and  tigers  take  only  from  three  to  five  years 
to  become  adult ;  both  sexes  are  capable  of  breeding,  and  the  males 
have  got  good  manes  soon  after  they  are  three  years  old,  but  they 
may  go  on  growing  for  several  years  after  that.  Leopards,  lynxes 
and  caracals  and  the  smaller  cats  generally,  take  from  one  and  a  half 
to  three  years  to  become  adult.  A  jaguar  cub  born  in  the  London 
Zoological  Gardens  was  not  nearly  half  grown  when  it  was  a  year 
old.  Although  it  was  brought  up  by  its  mother,  it  soon  became 


42  CHILDHOOD  OF  ANIMALS 

rickety  and  did  not  live  to  maturity,  so  that  its  rate  of  growth  was 
abnormal.  Caracals  are  a  good  deal  smaller  than  jaguars  or 
leopards,  and  their  cubs  are  nearly  full  grown  when  they  are 
a  year  old ;  probably  from  one  to  two  years  is  the  duration  of 
their  youth.  Bears  take  longer  to  grow ;  brown  bears  require 
nearly  six  years,  and  Polar  bears  still  longer  to  become  adult. 
The  fur  seal  has  been  observed  very  closely  in  its  breeding  haunts, 
and  it  has  been  ascertained  that  it  is  not  adult  until  it  is  four 
years  old,  but  both  sexes  and  especially  the  bulls  continue  to 
increase  in  size  after  that  age.  Among  domestic  dogs  there  is 
almost  an  exact  parallel  between  size  and  the  duration  of  youth. 
They  all  mature  quickly,  but  mastiffs  are  hardly  mature  at  two 
years  old,  large  hounds  and  greyhounds  at  about  eighteen  months, 
pointers  and  setters  at  from  eighteen  to  fifteen  months,  whilst 
fox  terriers  are  adult  at  about  a  year  and  toy  dogs  at  even  less. 

Badgers  are  born  in  February  or  the  beginning  of  March  and 
remain  with  the  mother  until  the  autumn,  when  they  look  after 
themselves.  They  are  practically  adult  at  a  year  old,  but  may 
continue  to  grow  for  another  six  months,  the  males,  as  in  most 
mammals,  taking  rather  longer  to  fill  out.  Otters  are  born  in 
almost  any  season  of  the  year  and  are  adult  in  about  ten  months, 
but  may  continue  to  grow  for  a  few  months  longer.  Weasels, 
martens  and  polecats  all  take  from  nine  to  eighteen  months  to  reach 
their  full  size. 

It  is  impossible  to  arrange  Carnivora  in  a  scale  extending  from 
the  highest  to  the  lowest  in  the  fashion  which  can  readily  be  done 
with  man  and  monkeys.  They  are  all  animals  of  a  high  type  and 
all  show  considerable  intelligence,  power  of  adapting  themselves  to 
new  situations,  acquiring  likes  and  dislikes  to  individuals,  and 
showing  their  distastes  and  preferences  in  the  plainest  way.  No 
doubt  memory  and  the  sense  of  locality  have  been  specially  developed 
in  the  dog,  because  of  its  long  association  with  man  and  from  the 
effect  of  selective  breeding  for  qualities  that  man  appreciates.  My 
tame  caracal,  which  came  from  a  stock  certainly  not  modified  by 
human  agency,  learned  the  ways  of  a  house  as  perfectly  as  any 
domestic  cat  or  dog.  He  allowed  himself  to  be  handled  by  those 
he  trusted  with  complete  confidence,  to  take  food  or  medicine  from 
a  spoon,  to  have  his  claws  cut  and  his  ears  cleaned  out  with  disin- 
fectant. He  disliked  being  left  alone  and  always  followed  his 
owners  from  room  to  room.  At  night,  before  going  to  bed,  he  went 
to  the  box  that  was  prepared  for  him,  and  then  came  to  have  his  feet 


DURATION  OF  YOUTH  IN  MAMMALS         43 

wiped,  a  process  he  much  disliked.  He  usually  slept  on  a  bath 
towel  alongside  my  pillow,  but  on  several  occasions,  for  various 
reasons,  he  slept  under  different  conditions,  sometimes  for  a  few 
days  at  a  time,  once  for  more  than  a  month.  On  coming  back  he 
at  once  went  to  his  old  place  without  any  hesitation.  It  is  the  instinct 
of  a  cat  to  pounce  on  any  moving  object,  and  he  had  some  difficulty 
in  learning  that  a  knee  or  a  foot  moving  under  the  bedclothes 
was  not  legitimate  prey.  But  he  learned  this,  and  he  never  had  to 
be  taught  not  to  lay  hold  of  the  face  or  hands.  If  it  were  cold  at 
night  and  he  wished  to  be  taken  under  the  blankets,  or  if  he  wished 
to  leave  the  room,  he  would  arouse  me  by  stroking  my  face  with  his 
paws.  I  believe  it  is  the  experience  of  every  one  who  has  been  at 
the  pains  to  make  friends  with  any  of  the  wild  Carnivora  that  they 
show  as  much  intelligence  as  the  domesticated  forms.  There  is 
no  parallel  between  size  and  intelligence  among  Carnivora  ;  the 
sizes  to  which  the  different  species  attain  seem  to  be  associated 
with  their  habits  of  life  rather  than  with  their  place  in  the  scale. 
Youth  lasts  longest  in  some  of  the  larger  forms  ;  in  all  of  them 
it  is  shorter  in  proportion  to  size  than  in  man  and  his  allies,  and  in 
most  of  them  it  is  absolutely  shorter  than  in  most  of  the  near 
relations  of  man.  If  the  two  groups  be  compared  with  regard  to 
size,  the  difference  is  very  striking ;  the  largest  carnivores,  such 
as  bears,  lions  and  tigers,  are  much  larger,  more  bulky  and  more 
powerful  animals  than  gorillas  and  chimpanzees,  but  reach  maturity 
much  more  quickly. 

The  vegetarian  terrestrial  mammals  belong  to  distinct  groups 
which  are  not  at  all  closely  related  and  which  must  be  considered 
separately. 

Elephants  are  the  largest  and  heaviest  of  existing  land  animals. 
The  African  elephant  reaches  a  greater  size  and  bulk  than  the 
Indian  species  ;  the  tallest  wild  specimen  whose  height  has  been 
recorded  was  shot  in  Abyssinia  and  stood  u  feet  8^  inches  at  the 
shoulder  ;  Jumbo,  the  largest  African  elephant  that  has  been  in 
captivity,  was  n  feet  high  when  he  left  the  London  Zoological 
Gardens,  and  is  stated  to  have  reached  12  feet  before  he  died  in 
America.  An  Indian  elephant  10  feet  6  inches  in  height  is  unusually 
large.  A  moderately  sized  elephant,  of  about  7  feet  high,  weighs 
from  2  to  3  tons,  and  a  really  fine  example  between  5  and  6  tons, 
Jumbo  having  weighed  6J  tons.  Elephants  grow  slowly  ;  the  dura- 
tion of  their  youth  is  from  twenty  to  twenty -four  years,  a  very  much 
longer  time  than  that  occupied  by  the  youth  of  any  other  terrestrial 


44  CHILDHOOD  OF  ANIMALS 

mammal  except  man.  If,  however,  we  remember  that  a  full- 
grown  elephant  weighs  as  much  as  fifty  full-grown  men,  and  that 
these  animals  have  some  difficulty  in  obtaining  the  enormous 
quantities  of  food  they  require,  the  length  of  their  youth  is  not  so 
remarkable.  I  think  that  their  intelligence  has  been  not  a  little 
over -praised.  They  are  docile,  except  at  special  periods  of  their 
life,  and  can  be  taught  to  perform  different  kinds  of  simple  labour 
and  to  obey  commands.  But  even  in  the  case  of  the  highly  trained 
animals  of  the  circus  ring,  if  the  tricks  be  carefully  studied  it  will 
be  seen  that  they  require  none  of  the  mental  powers  shown  by  dogs, 
cats,  sea-lions  or  monkeys.  Trainers  of  elephants  have  told  me 
that  they  can  count  on  no  powers  of  imitation  or  originality  on 
the  part  of  their  pupils,  but  have  to  teach  the  animals  each  distinct 
movement  of  the  performance  separately.  Elephants  have  good 
memories,  and  take  strong  likes  or  dislikes  to  individuals,  but  those 
best  acquainted  with  them  disbelieve  the  familiar  stories  as  to  their 
saving  the  lives  of  their  keepers  and  so  forth. 

There  is  no  group  of  living  animals  closely  related  to  the  elephants, 
but  it  is  probable  that  the  hyraces,  rock -rabbits  or  dassies  are  their 
nearest  allies.  The  largest  of  these  animals  is  no  bigger  than  a  hare, 
and  there  are  different  species  found  in  Syria,  Arabia  and  Africa. 
As  they  practically  never  breed  in  captivity,  not  much  is  known 
about  their  youth.  I  had  a  young  West  African  tree-hyrax  brought 
to  me  recently  which  had  been  taken  by  its  owner  when  it  was  in  his 
opinion  only  a  few  days  old,  and  which  at  six  months  old  was 
not  half  grown.  It  is  probable,  therefore,  that  the  youth  of 
these  animals  lasts  more  than  a  year.  I  had  never  seen  a  tame 
tree-hyrax  before,  and  this  little  animal  interested  me  very  much. 
Its  owner,  who  was  a  mining  engineer,  did  not  happen  to  know 
anything  about  the  natural  habits  of  his  pet,  except  that  it  lived  in 
the  tops  of  tall  forest  trees.  He  could  not  get  it  to  eat  for  some  time, 
and  in  despair  stuffed  it  with  bread  and  milk.  It  ate  on  its  own 
account  afterwards,  but  usually  required  to  be  coaxed,  which  he 
did  by  making  a  sucking  noise  with  his  mouth  and  pretending  to  eat 
himself.  Persuaded  in  tjiis  way,  it  took  milk  with  rice,  bread  or 
biscuit,  hard-boiled  egg,  apple,  lettuce  and  even  pieces  of  cooked 
fish.  It  liked  companionship,  following  its  owner  about.  It 
made  itself  at  home  in  my  house  at  once,  exploring  everything, 
clinging  up  the  legs  of  chairs  and  on  the  shelves  of  bookcases, 
generally  making  a  low  chirping  purr.  It  liked  rubbing  its  fur  and 
especially  the  white  hair  along  the  glandular  patch  on  its  back  against 


DURATION  OF  YOUTH  IN  MAMMALS          45 

my  clothes.  When  it  was  angry  it  stamped  with  its  fore-paws  on 
the  ground.  It  had  quite  an  unusual  degree  of  character  and 
intelligence,  and  a  most  restless  curiosity. 

The  Odd-toed  Ungulates,  the  rhinoceros,  the  horse  and  the  tapir, 
have  a  period  of  youth  the  length  of  which  is  roughly  in  proportion 
to  the  size  of  the  animals,  but  which  is  relatively  rather  shorter 
than  that  of  the  elephant  and  the  hyrax.  A  young  ihinoceros 
grows  very  quickly  at  first  and  runs  with  its  mother  until  it  is  nearly 
full  grown.  The  limit  of  size  varies  a  good  deal  in  the  different 
species,  and  actual  growth  appears  to  go  on  for  a  great  many  years, 
but  so  far  as  can  be  ascertained  the  animals  are  adult  at  seven  or 
eight  years  of  age.  Horses  and  asses  have  been  much  influenced 
by  domestication,  and  the  period  of  youth  has  been  made  shorter  in 
some  of  the  breeds.  Horses,  asses  and  zebras  are  certainly  adult  at 
five  years  of  age,  and  the  average  duration  of  the  period  of  youth  is 
less,  probably  from  three  to  four  years.  Tapirs  mature  very 
quickly  ;  when  they  are  born  they  are  striped  and  blotched  with 
white,  so  that  they  are  very  unlike  their  parents  (see  Plate  VI, 
p.  94).  In  four  to  six  months  this  youthful  coloration  disappears 
and  they  resemble  their  parents  in  pattern.  The  duration  of 
their  youth  is  said  to  be  under  a  year,  a  very  short  time  for  animals 
of  their  size,  but  certainly  some  individuals  at  least  continue  to  grow 
for  much  more  than  a  year.  The  rhinoceros  and  the  tapir  are 
rather  unintelligent  animals  with  low  mental  powers.  The  horse 
has  been  so  much  modified  by  association  with  man  and  by 
selection  for  special  qualities  which  are  useful  or  pleasant  that 
we  are  disposed  to  have  a  false  idea  of  its  mental  powers.  I 
rate  them  low  as  compared  with  monkeys,  carnivores  or  even 
elephants. 

The  Even-toed  Ungulates  have  a  still  shorter  duration  of  youth  in 
proportion  to  their  size.  Those  that  do  not  ruminate,  the  hippo- 
potamus and  the  swine  and  peccaries,  have  often  bred  in  captivity, 
and  we  have  therefore  accurate  information  about  them.  The 
hippopotamus  is  a  very  large  animal,  a  good  male  reaching  over 
14  feet  in  length  and  weighing  well  over  4  tons.  They  are  fully 
adult  in  five  or  six  years,  although  they  may  continue  to  increase 
in  bulk  for  some  time  after  that.  Swine  of  different  kinds  come  to 
maturity  in  from  eighteen  months  to  two  years,  although  they  also 
may  continue  to  increase  in  size  for  a  longer  period.  The  hippo- 
potamus is  certainly  a  stupid  animal,  and  I  do  not  believe  in  the 
intelligence  of  pigs.  The  tricks  of  trained  animals,  such  as  the 


46  CHILDHOOD  OF  ANIMALS 

learned  pigs  of  country  fairs,  are  very  simple  adaptations  of  theiri 
natural  instincts,  and  are  no  evidence  for  the  existence  of  any  real 
mental  capacity. 

The  Ruminating  Ungulates  without  exception  have  a  very  short 
duration  of  youth  in  proportion  to  their  size,  and  could  be  arranged 
in  an  almost  regular  series  in  which  size  and  duration  of  youth  were 
parallel.  Giraffes  are  the  largest,  and  their  period  of  youth  lasts 
from  six  to  seven  years.  Camels  are  adult  in  three  years,  llamas 
and  alpacas  in  rather  less.  Domestic  cattle  are  adult  in  about  two 
years.  Bison  take  between  two  and  three  years,  and  increase  in 
size  for  rather  longer.  The  very  large  deer  like  elk  are  adult  in  two 
years,  but  may  continue  to  increase  in  size  for  a  longer  period;  whilst 
in  them  as  in  other  deer,  although  there  may  not  be  much  increase 
in  actual  size,  the  antlers  become  more  spreading  and  acquire 
more  points  for  many  years  after  maturity  has  been  attained. 
Elands,  which  are  the  largest  of  the  antelopes,  are  mature  in  three 
to  four  years.  Many  of  the  little  duikers  reach  their  full  size  and 
are  adult  in  about  twelve  to  eighteen  months.  The  range  of  the 
period  of  youth  in  the  whole  group  of  ruminants  lies  between  seven 
years  and  one  year  and  follows  the  size  of  the  animal  rather 
closely.  It  will  be  generally  agreed  that  ruminants  are  animals  of 
low  intelligence. 

We  have  not  much  information  as  to  the  duration  of  youth  in. 
the  marsupials.  The  large  kangaroos  leave  the  pouch  of  the  mother 
permanently  in  from  six  to  seven  months.  They  grow  very  quickly 
immediately  afterwards,  and  are  fully  adult  in  from  one  to  two 
years.  The  smaller  forms  develop  still  more  quickly  and  are 
fully  adult  in  from  six  months  to  a  year. 

Rodents  differ  much  in  size  and  in  intelligence.  Beavers  are  not 
the  largest  members  of  the  group,  but  they  are  larger  than  most,  and 
much  more  intelligent  than  any  of  the  others.  They  begin  to  pah* 
when  they  are  two  years  old  and  are  fully  grown  at  the  end  of 
the  third  year,  so  that  the  duration  of  their  youth  may  be  reckoned 
as  being  between  two  and  three  years.  Hares  may  begin  to  breed 
when  they  are  a  year  old  and  are  fully  grown  in  fifteen  months. 
Rabbits  have  a  shorter  youth ;  they  pair  when  they  are  from  five 
to  eight  months  old,  and  are  fully  grown  in  a  year.  Guinea-pigs 
may  begin  to  breed  when  they  are  three  or  four  months  old  and  are 
Jull  grown  in  from  five  to  six  months.  Rats,  which  are  born  naked 
and  blind,  are  covered  with  hair  on  the  eightlTciay,  and  are  able  to  see 
on  the  thirteenth  day.  On  the  twenty -first  day  they  have  reached 


DURATION  OF  YOUTH  IN  MAMMALS          47 

the  size  of  a  house  mouse,  and  are  turned  out  to  shift  for  themselves 
when  they  are  thirty -nine  days  old.  They  begin  to  breed  when  they 
are  less  than  six  months  old  and  are  fully  grown  a  few  months  later. 
Mice  will  breed  when  they  are  six  weeks  old  and  are  fully  grown  at 
three  to  four  months  old. 

I  do  not  think  that  it  is  necessary  to  go  on  giving  any  more 
examples.  It  is  clear  that  different  kinds  of  mammals  pass  through 
very  different  periods  of  time  in  growing  to  adult  life.  There  is 
certainly  some  relation  between  size  and  the  duration  of  youth. 
On  the  whole  it  takes  a  longer  time  to  grow  into  a  big  animal  than 
into  a  small  animal.  But  the  relation  is  not  so  close  that  it  can  be 
explained  in  a  simple  fashion.  The  youth  of  civilised  man  and  of 
the  elephant  lasts  about  the  same  number  of  years.  A  common 
monkey  and  a  lion  take  about  the  same  time  to  grow  up.  The  North 
American  beaver  and  the  bison  take  very  nearly  the  same  time, 
although  the  latter  is  several  hundred  times  the  bulk  of  the  former. 
Nor  is  there  any  part  of  the  processes  of  nature  which  might  lead 
us  to  expect  an  inseparable  link  between  time  and  bulk.  The 
different  cells  and  tissues  of  the  individual  body  grow  at  different 
rates,  and  these  rates  may  change  at  the  call  of  circumstances  that 
have  nothing  to  do  with  size.  Temperature,  moisture,  the  nature 
of  the  food  and  many  other  agencies  alter,  retard  or  accelerate  the 
pace.  There  seems  to  be  a  very  wide  range  within  which  the  same 
organs  and  tissues  or  the  same  kinds  of  animals  or  plants  may  grow 
more  quickly  or  slowly.  None  the  less,  it  is  reasonable  to  suppose 
that  closely  allied  animals  have  more  or  less  similar  constitutions, 
and  such  a  conclusion  is  supported  by  many  physiological  obser- 
vations. They  have  similar  habits,  they  react  in  similar  fashions 
to  the  same  diseases,  and  betray  their  community  of  blood  by 
responding  to  similar  environments  in  similar  ways.  And  so  com- 
parisons between  the  duration  of  youth  and  the  size  of  the  adult  are 
less  misleading  when  they  are  made  inside  the  various  groups. 
I  have  shown  that  on  the  whole  the  larger  animals  of  a  group  take 
longer  to  grow  up  than  the  smaller  animals  of  the  same  group. 
But  the  parallel  is  not  exact,  and  there  are  many  exceptions,  as,  for 
instance,  among  the  Garni vora.  On  the  other  hand,  the  higher, 
the  more  intelligent  members  of  a  group  are  usually  the  larger 
animals.  Here  again  there  are  exceptions,  but  on  the  whole  it  is 
true  of  living  groups  and  of  the  total  procession  of  life  in  the  past. 
Mammals  form  the  highest  class  of  living  animals,  and  amongst 
mammals  are  to  be  found  the  largest  existing  members  of  the  animal 


48  CHILDHOOD  OF  ANIMALS 

kingdom.  In  the  age  of  Reptiles,  when  they  were  the  lords  of 
creation,  the  largest  existing  animals  were  reptiles.  In  the  age  of 
Batrachians  the  largest  existing  creatures  were  batrachians.  A  ad  so 
inside  the  orders  of  living  mammals,  they  are,  on  the  whole,  the  most 
highly  organised  creatures  that  have  been  able  to  increase  in  size. 
Certainly  there  are  many  advantages  in  being  big.  A  bulky  animal 
can  resist  changes  in  temperature  better  than  a  smaller  creature, 
which  may  be  more  quickly  overheated  or  chilled  through.  A  big 
animal,  other  things  being  equal,  is  more  powerful  and  can  protect 
itself  better  and  travel  greater  distances  than  a  smaller  animal  of  the 
same  kind.  But  there  are  also  great  disadvantages.  A  big  animal 
needs  more  food  than  a  smaller  one,  and  can  less  easily  escape 
the  observation  of  its  enemies.  The  struggle  for  existence  is 
specially  keen  among  animals  with  similar  habits  and  structure, 
and  amongst  these  it  is  the  more  highly  organised  and  intelligent 
that  can  become  large  with  least  risk.  Amongst  mammals  I  do 
not  doubt  but  that  the  apparent  connection  between  the  duration 
of  youth  and  the  size  is  secondary  ;  both  depend  on  intelligence 
It  is  the  more  intelligent  animals  that  have  the  longest  period  of 
youth. 

In  the  beginning  of  this  chapter  I  spoke  of  the  lengthening  of  the 
period  of  youth  in  our  own  case,  even  in  our  own  time.  Breeders 
of  domesticated  animals  have  found  that  they  can  prolong  or  shorten 
the  duration  of  youth  in  the  case  of  farm  stock.  There  are  many 
instances  showing  that  wild  animals  in  captivity  mature  more 
quickly  in  some  cases,  more  slowly  in  other  cases,  than  their  fellows 
under  natural  conditions.  The  series  of  animals  in  the  different 
orders  of  mammals  show  that  there  is  an  increase  in  the  duration  of 
youth  as  we  pass  from  the  lower  forms  to  the  higher  forms.  Putting 
these  different  sets  of  observations  together,  we  must  draw  the  conclu- 
sion that  the  rate  of  growth  in  animals  has  been  altered  in  the  course 
of  evolution,  and  in  such  a  fashion  as  to  prolong  youth  in 
the  higher  forms.  This  lengthening  of  youth  is  not  completely 
explained  by  increase  of  size,  nor  even  by  increased  complexity  of 
structure.  Its  advantage  is  that  it  gives  the  opportunity  for  education 
in  the  widest  sense  of  the  word,  a  space  for  experiment  and  for  the 
replacing  of  instinct  by  intelligence. 


CHAPTER  IV 

THE  DURATION  OF  YOUTH  IN  BIRDS  AND 
LOWER  ANIMALS 

BIRDS  show  Nature  in  her  most  luxuriant  and  inventive  mood. 
There  seems  to  be  an  infinite  variety  in  size,  habits,  disposition  and 
colouring,  and  yet  these  many  differences  conceal  a  similarity  of 
structure  so  close  that  there  is  a  smaller  gap  between  the  ostrich 
and  the  humming-bird,  or  between  the  flamingo  and  the  wren,  than 
exists  between  many  members  of  the  same  order  of  mammals. 
For  our  present  purpose  they  may  be  considered  as  a  single  group, 
without  reference  to  the  divisions  into  which  systematists  have 
been  able  to  place  them.  I  have  already  said  that  attempts  have 
been  made  to  find  some  relation  between  the  duration  of  the  period 
of  youth  and  the  whole  life.  Such  attempts  would  fail  completely 
in  the  case  of  birds.  It  is  a  curious  fact  that  in  proportion  to  their 
size,  birds  are  longer  lived,  or  at  least  have  a  higher  potential 
longevity,  than  mammals.  If  we  compare  them,  group  by  group, 
mammals  are  much  larger  than  birds,  herbivorous  mammals  than 
herbivorous  birds,  frugivorous  mammals  than  frugivorous  birds, 
omnivorous  and  carnivorous  mammals  than  omnivorous  and  car- 
nivorous birds.  And  yet,  group  by  group,  birds  approach  or 
surpass  mammals  in  longevity.  Passerine  birds,  which  range  in 
size  from  minute  creatures  which,  stripped  of  their  feathers,  are  no 
larger  than  the  tiniest  shrew-mouse,  to  the  large  ravens,  have  a 
potential  longevity  ranging  from  twenty  to  sixty  years.  Owls  and 
parrots  certainly  can  live  for  half  a  century,  and  eagles  and  vultures 
much  longer.  Pelicans  and  storks  may  live  for  from  fifty  to  thirty 
years,  ducks  and  geese  much  longer,  pigeons  and  gulls  for  thirty 
years,  ostriches  for  fifty  years.  Compared  with  these  figures  the 
duration  of  youth  is  always  short,  and  ranges  from  about  two  to 
three  or  four  years.  Ostriches,  which  are  the  largest  living  birds, 
take  from  three  to  four  year's  to  become  full  grown  and  adult,  but 
birds-of -paradise  take  nearly  the  same  time.  Condors  and  the 
larger  birds-of -prey  are  as  big  as  a  hen  when  they  are  a  month  old, 
but  take  rather  more  than  three  years  to  reach  their  full  size.  The 

C.A.  49  D 


50  CHILDHOOD  OF  ANIMALS 

smaller  birds-of-prey,  such,  for  instance,  as  turkey- vultures,  are 
full  grown  at  two  years  old.  Fowls  and  pheasants  are  full  grown 
at  the  end  of  their  second  year,  whilst  flamingoes,  which  are  much 
larger  birds,  take  less  than  two  years  to  become  adult.  The  dura- 
tion of  youth  in  birds  is  therefore  remarkably  constant ;  it  varies, 
from-  about  one  year  to  nearly  four  years.  There  is  very  little  relation) 
between  size  and  the  length  of  youth.  As  the  intelligence  of 
birds  is  very  remote  from  that  of  our  own,  it  is  most  difficult  to 
estimate  which  are  higher  and  lower  in  this  respect.  But  on  the 
whole  it  must  be  said  that  birds  are  much  more  instinctive  than 
mammals,  that  their  various  duties  are  performed  in  a  more  rigid 
and  mechanical  fashion,  and  that  there  is  therefore  less  scope  than 
amongst  mammals  for  the  experimental  period  of  youth. 

Reptiles  live  to  great  ages.  They  grow  very  slowly  and 
many  of  them  appear  to  go  on  growing  throughout  their  lives. 
Although  there  are  considerable  differences  in  size  between  different 
adult  individuals  of  the  same  species  in  both  birds  and  mammals, 
on  the  whole  it  may  be  said  that  each  species  has  a  rather  precisely' 
limited  range  of  adult  size,  and  that  individuals  outside  the  limitsi 
of  this  range  are  abnormal — in  fact,  are  dwarfs  or  giants.  The 
dimensions  of  the  skull  or  of  the  body  in  adults  are  often  so  much 
alike  in  a  large  number  of  individuals  that  they  are  useful  characters 
in  defining  and  identifying  species.  This  is  not  the  case  with 
reptiles.  No  doubt  there  are  limits  beyond  which  crocodiles  or 
pythons  do  not  grow,  and  there  are  large  lizards  and  small  lizards; 
large  serpents  and  small  serpents.  But  as  compared  with  birds) 
and  mammals,  the  different  species  have  not  a  fixed  size.  The  rate 
of  growth,  moreover,  is  much  more  dependent  on  surrounding 
conditions,  particularly  on  temperature.  Birds  and  mammals  have 
an  automatic  system  of  regulating  the  temperature  of  their  bodies. 
In  our  own  case,  our  normal  temperature  of  98.6°  remains  nearly 
constant  whether  we  are  exposed  to  the  cold  of  winter  or  the  heat 
of  summer  ;  if  it  goes  up  a  degree  or  goes  down  a  degree  we  feel 
uncomfortable,  and  if  we  found  it  to  be  100°  or  96°  we  should 
know  that  we  were  ill  and  that  there  was  some  disorder  interfering 
with  the  routine  of  our  physiological  processes.  So  also  each  kind 
of  bird  and  mammal  has  its  normal  temperature,  not  quite  so 
stable  as  that  of  man,  but  during  health  kept  fairly  constant. 
Reptiles,  on  the  other  hand,  like  batrachians,  fishes  and  probably! 
most,  if  not  all,  invertebrates,  have  not  a  normal  temperature,  but 
go  up  and  down  with  the  temperature  of  the  air  or  water  with 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     51 

which  they  are  surrounded  and  are  thus  almost  at  the  mercy  of 
the  elements.  If  they  become  too  hot  or  too  cold  they  first  get  torpid, 
and  if  the  conditions  continue  they  die.  Reptiles  will  not  feed  or 
grow  unless  they  are  kept  warm.  In  the  Reptile  House  of  the 
London  Zoological  Gardens  the  heating  apparatus  was  greatly 
improved  in  the  year  1911 ;  the  reptiles  were  much  more  lively  and 
active,  and  the  rather  unexpected  result  occurred  that  the  food 
bill  was  nearly  doubled.  In  the  varying  conditions  of  nature,  a 
succession  of  warm  seasons  or  of  cold  seasons  must  affect  the  rate 
of  growth  of  reptiles  to  a  very  large  degree,  and  it  is  not  surprising 
that  we  can  tell  little  of  the  age  of  any  individual  from  its  size.  Very 
few  reptiles  breed  in  captivity,  whilst  in  the  wild  condition  their 
shy  habits  make  it  difficult  to  observe  them  closely.  There  is  the 
further  difficulty  that  young  reptiles  from  the  first  are  remarkably 
like  their  parents.  And  so  it  happens  that  we  have  practically  no 
information  regarding  the  duration  of  youth  in  reptiles. 

The  sizes  to  which  the  different  species  of  frogs,  toads  and  newts 
may  reach  vary  within  wider  limits  than  those  of  birds  and  mammals, 
but  it  is  curious  that  the  range  is  narrower,  especially  in  the  case 
of  the  tailless  land  forms,  than  occurs  with  reptiles.  Batrachians 
are  less  shy  in  their  breeding  habits  than  are  reptiles,  and  many 
of  them  have  been  bred  and  reared  in  captivity.  In  the  case  of 
those  that  breed  in  water  and  pass  through  a  metamorphosis,  the 
spawn  is  usually  laid  very  early  in  the  year,  but  this  depends 
partly  on  temperature.  In  cold  seasons  it  may  be  delayed  for  some 
weeks,  and  in  England,  except  at  considerable  levels  above  the 
sea,  it  usually  occurs  early  in  March.  I  have  found  the  spawn  of 
the  common  grass  frog  in  mountain  bogs  in  Scotland  late  in  June. 
The  tadpoles  of  the  common  frog  begin  to  leave  the  eggs  in  about 
five  days,  and  in  about  two  months  the  legs  have  appeared,  whilst 
the  metamorphosis  is  complete  and  the  frogs  leave  the  water  in 
nearly  three  months.  The  development  of  the  common  toad  is 
not  quite  so  rapid.  The  tadpoles  leave  the  eggs  in  about  ten  days, 
but  the  two  pairs  of  limbs  are  not  fully  formed  for  about  eighty 
days,  whilst  the  young  toads  leave  the  water  relatively  smaller  than 
frogs,  when  they  are  a  little  more  than  three  months  old.  They 
may  begin  to  breed  long  before  they  are  full  grown,  but  they  take 
from  three  to  five  years  to  reach  the  normal  size.  The  possible 
duration  of  their  life  is  unknown,  but  they  have  so  many  enemies 
that  probably  few  have  the  luck  to  reach  old  age. 

Fish,  like  reptiles,  grow  slowly  and  may  live  to  great  ages.     In 


52  CHILDHOOD  OF  ANIMALS 

them,  as  in  reptiles,  although  there  are  species  which  may  reach  a 
large  size  and  species  the  members  of  which  are  always  small, 
there  is  a  very  wide  range  of  size  for  each  species,  and  growth 
appears  to  go  on  continuously  throughout  life.  As  in  the  case  of 
reptiles,  the  rate  of  growth  varies  with  external  conditions,  partly 
those  of  temperature,  but  still  more  the  nature  and  amount  of  the 
food-supply.  In  many  fish  there  are  annual  ring-like  markings  on 
the  scales,  and  in  others  in  the  concretions  found  in  the  internal 
ear,  and  known  as  otoliths,  by  which  the  age  can  be  estimated,  in 
the  same  way  as  the  age  of  a  tree  can  be  ascertained  by  counting 
the  annual  rings  of  growth  visible  when  the  stem  is  cut  across. 
Experiments  made  by  transferring  marked  fish  from  places  where 
the  food-supply  is  scanty  to  places  where  it  is  abundant  have  shown 
that  the  size  of  a  fish  cannot  be  taken  as  an  indication  of  its  age. 
The  eggs  of  fish  take  from  about  three  to  over  a  hundred  days  to 
hatch  out,  but  the  time  varies  a  good  deal  according  to  the  tempera- 
ture of  the  water.  As  a  rule  the  eggs  of  smaller  fish  hatch  more 
quickly  than  those  of  larger  fish,  but  a  more  important  difference 
depends  on  the  size  of  the  egg.  Small  eggs  with  very  little  yolk 
hatch  quickly,  and  the  larvae  on  their  appearance  are  in  a  more 
rudimentary  condition.  Those  with  an  abundant  supply  of  yolk 
take  longer  to  hatch,  but  the  larvae  are  relatively  larger  and  more 
highly  developed.  As  cold  water  delays  development  and  retards 
the  period  of  hatching,  the  larvae  usually  appear  when  the  water  is 
warm  and  when  there  is  an  abundant  supply  of  the  microscopic 
organisms  on  which  they  feed.  Growth  is  then  rapid  and  in  most 
cases  the  larvae  become  transformed  into  small  fish  like  the  adults 
in  the  course  of  their  first  season.  The  subsequent  history  varies 
much  in  different  kinds  of  fish.  In  those  where  the  larvae  and  the 
adults  live  under  practically  the  same  conditions,  the  sexual  organs 
often  mature  next  season,  and  although  the  fishes  may  be  small, 
their  period  of  youth  is  over.  Often  there  is  a  migration  from 
inshore  water  to  deep  water,  to  the  bottom  of  the  sea,  or,  in  the 
case  of  fresh  water,  from  the  shallow  fringes  of  lakes  or  from  upland 
streamlets  to  deep  water  or  to  the  lower  parts  of  rivers,  and  the 
change  to  adult  life  may  take  more  than  a  season.  In  fishes  where 
there  is  a  complete  change  of  habitat  the  youth  may  be  further 
prolonged.  The  larvae  of  the  salmon,  called  parr  or  samlets,  are 
hatched  in  the  spring  in  the  fresh-water  pools  where  the  spawn  has 
been  deposited.  They  remain  in  the  rivers  usually  for  about  two 
years,  slowly  losing  their  youthful  uniform  of  red  spots  and  dark 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     53 

bars  and  acquiring  a  silvery  colour.  In  the  spring  of  the  third 
year  they  go  down  to  the  sea  as  smolts,  which  display  a  much  darker 
and  more  mottled  coloration  than  salmon.  In  the  sea  they 
rapidly  mature,  becoming  silvery  all  over  and  developing  their 
sexual  organs.  They  then  ascend  the  rivers  to  breed,  and  their 
duration  of  youth  is  thus  at  least  three  years,  although  from  the 
great  change  of  size,  a  smolt  weighing  only  a  few  ounces  and  a 
grilse  four  or  five  pounds,  it  has  been  supposed  that  the  young 
fish  may  remain  more  than  a  single  year  in  the  sea.  The  fresh- 
water eels  migrate  to  the  sea  to  spawn  and  lay  their  eggs  at  great 
depths.  These  hatch  out  into  ribbon-shaped  larvae  with  very 
small  heads.  These  little  fish  have  been  known  as  Leptocephali 
for  many  years,  the  different  kinds  of  them  receiving  different 
specific  names  before  it  was  discovered  that  they  were  the  larvae 
of  different  kinds  of  eels.  The  larva  of  the  common  eel,  formerly 
known  as  Leptocephalus  brevirostris,  grows  rapidly  until  it  becomes 
about  two  and  a  half  inches  long,  when  it  passes  through  meta- 
morphosis and  becomes  transformed  to  a  small  eel,  which,  curiously, 
is  only  about  two  inches  long.  These  small  eels  leave  the  bottom 
of  the  sea  and  come  up  towards  the  coast  when  they  are  about  a 
year  old.  They  then  enter  fresh  water,  ascending  the  rivers  in 
great  numbers,  and  at  night  migrating  from  stream  to  stream  across 
wet  grass.  They  live  for  a  number  of  years  before  they  become 
adult,  the  largest  size  to  which  the  females  attain  being  a  little 
over  a  yard,  that  of  males  being  much  less.  Then  the  sexual  organs 
begin  to  develop,  the  process  taking  several  months,  duiing  which 
the  eels  cease  to  feed.  They  then  migrate  down  to  the  sea,  and 
when  they  have  reached  deep  water,  probably  more  than  a  hundred 
fathoms,  spawning  takes  place  and  the  eels  die.  This  is  a  curious 
instance,  very  unusual  amongst  vertebrate  animals,  but  common 
in  insects  where  nearly  the  whole  life  of  the  animal  may  be  occupied 
by  the  period  of  youth.  It  seems  to  be  the  case  that  eels  spawn 
only  once,  and  that  however  long  they  live,  or  whatever  size 
they  attain,  they  must  be  regarded  as  still  in  the  youthful  period 
until  they  have  ceased  to  feed  and  have  begun  to  spawn. 

All  the  vertebrate  animals  have  a  structure  not  remote  from  our 
own,  a  nervous  system  consisting  of  a  brain  and  spinal  cord,  and 
organs  of  smell,  sight  and  hearing  essentially  similar  to  our  nose, 
eyes  and  ears.  Amongst  them  we  are  on  familiar  ground,  and  have 
some  reason  to  suppose  that  we  can  interpret  their  mental  operations 
and  emotions  with  a  sympathetic  intelligence.  The  bond  is  most 


54  CHILDHOOD  OF  ANIMALS 

close  between  us  and  the  higher  monkeys  and  gets  more  and  more 
remote  as  we  pass  through  the  various  orders  of  mammals  and 
descend  through  birds  to  reptiles,  and  from  them  to  batrachians 
and  fishes.  Fear  and  anger,  cowardice  and  bravery,  dislike  and 
affection,  the  relations  of  individuals  to  individuals  and  of  species 
to  species,  may  differ  in  quality  and  degree,  but  appear  to  be 
essentially  similar  in  kind  in  all  these  different  sets  of  animals. 
They  are  all  in  mental  touch  with  their  environment  in  the  same 
sort  of  fashion.  I  think  that  we  must  be  right  in  interpreting  the 
phases  of  their  life  by  the  same  kind  of  standards  that  we  can  apply 
to  our  own  case.  The  duration  of  youth  in  all  is  settled  by  no 
invariable  chain  of  organic  necessity.  It  has  no  relation  to  the 
duration  of  the  complete  cycle  of  life  from  birth  to  death.  It  is 
linked  with  size,  but  only  in  an  indirect  fashion,  most  apparent  in 
animals  most  akin.  It  is  linked  much  more  closely  with  complexity 
of  organisation,  so  that  the  higher  forms  usually  take  longer  to 
mature  than  their  near  but  lower  relations.  It  is  linked  most 
closely  with  intelligence,  the  more  intelligent  animals  having 
relatively  longer  youth.  And  as  we  pass  downwards  from  intelli- 
gence to  instinct  we  find  that  the  duration  of  youth  shortens. 

The  case  of  the  eel,  where  the  adult  life  is  only  a  very  small 
portion  of  the  total  length  of  life,  is  not  so  curious  as  the  cases  of 
many  insects.  Among  insects  there  are  all  gradations  between 
creatures  which  live  only  a  few  weeks  and  creatures  which  enjoy 
life  for  many  years.  Insects,  however,  are  very  closely  dependent 
on  temperature,  partly  indirectly  because  their  food-supply  often 
ceases  in  cold  weather,  and  partly  directly  because  they  become 
torpid  and  die  when  their  bodies  are  subjected  to  cold.  The  dura- 
tion of  life  of  most  insects  is  limited  to  less  than  a  year.  The  eggs 
hatch  out  when  the  temperature  has  become  sufficiently  high,  the 
larvae  grow  bigger,  pass  through  their  metamorphoses  and  become 
transformed  to  the  adult  in  the  same  season.  The  life  of  most  of 
the  adults  ceases  when  the  cold  of  winter  comes  on,  if  it  lias  not 
been  arrested  sooner  ;  but  the  species  maintains  existence,  either 
because  the  eggs  are  laid  in  a  position  where  they  may  lie  dormant 
until  next  spring,  or  because  a  few  of  the  adults  hibernate  in  some 
sheltered  place.  Sometimes  the  total  life  is  limited  to  a  very  short 
part  of  a  single  season.  In  many  of  the  plant-lice,  for  instance,  the 
little  green  flies  which  plague  the  gardener,  the  total  life  lasts  only 
two  or  three  weeks.  The  eggs  are  laid,  the  larvae  are  hatched, 
mature,  become  adult,  and  die  all  within  a  month.  The  total  life 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     55 

of  common  flies  such  as  the  blow-fly  and  the  house-fly  is  a  little 
longer.  The  blow-fly  hatches  out  in  twenty-four  hours,  the  larva 
takes  a  fortnight  to  grow,  whilst  the  metamorphosis  within  the 
pupa  case  takes  a  fortnight  in  warm  weather,  and  much  longer 
when  it  is  cold.  The  normal  life  of  the  adult  fly  is  from  a  few  days 
to  a  few  weeks,  or  in  specially  favourable  circumstances,  a  few 
months.  The  length  of  the  larval  life  of  butterflies  and  moths 
varies  according  to  the  size,  the  habits  and  the  weather,  and  as  in 
extreme  cases  the  life  of  the  adult  may  last  a  good  many  months,  it 
is  possible  that  the  total  cycle  may  sometimes  extend  a  little  over  a 
year.  Amongst  bees,  the  larval  life  and  the  metamorphosis  occupy 
at  most  a  few  weeks,  whilst  the  life  of  the  adult  is  relatively  longer. 
Worker  bees  never  live  beyond  the  year  in  which  they  are  produced  ; 
whilst  the  life  of  drones  may  be  only  a  few  days,  and  is  never  more 
than  a  few  months,  as  towards  the  end  of  the  season,  when  honey  is 
getting  scarce,  they  are  driven  out  of  the  hive  to  perish.  Queen 
ibees  may  live  from  two  to  five  years  ;  they  are  fed  and  cared  for  by 
the  workers,  and  their  confinement  to  the  hive  after  the  nuptial 
flight  preserves  them  from  the  vicissitudes  of  the  weather. 

The  instances  that  I  have  given  do  not  show  any  great  eccentricity 
in  the  distribution  of  the  total  duration  of  life  between  the  youthful 
and  the  adult  stages.  The  proportion  between  the  duration  of 
youth  and  of  adult  life  certainly  varies,  but  not  much  more  than  it 
varies  in  higher  animals,  and  we  do  not  know  enough  about  the 
physiology  of  insects  to  assign  reasons  for  these  different  durations, 
and  still  less  are  we  able  to  draw  parallels  between  the  lengths  of 
the  period  of  youth  and  the  degrees  of  intelligence.  The  mental 
processes  of  insects  and  their  modes  of  communication  with  the 
exterior  are  so  unlike  our  own  that  our  attempts  to  discriminate 
between  instinct  and  intelligence  must  be  the  most  casual  guesses. 
In  very  many  insects,  however,  the  disproportion  between  adult 
life  and  larval  life  is  so  great  that  adult  life  appears  to  have  been 
reduced  merely  to  the  time  required  for  reproduction.  Many  adult 
moths  and  butterflies  have  no  mouths  and  do  not  feed.  The  males 
live  only  long  enough  to  meet  and  fertilise  the  other  sex,  and  the 
females  live  a  little  longer,  apparently  only  because  they  have  to 
seek  out  food-plants  or  places  specially  suitable  for  the  larvae  which 
will  hatch  out  from  the  eggs  they  lay.  The  eggs  of  the  mayflies 
are  dropped  into  the  water  and  in  a  few  months  hatch  out  into 
creeping  campodeiform  larvae.  These  live,  according  to  the  species, 
from  six  months  to  three  years  in  the  water,  and  then  come  up  to  the 


56  CHILDHOOD  OF  ANIMALS 

surface,  usually  creeping  out  on  the  banks.  The  larval  integument 
then  splits  open  and  a  creature  which  has  the  form  of  a  winged 
insect  and  seems  able  to  fly  emerges.  This,  however,  goes  through 
another  moult,  generally  within  a  few  minutes  or  hours  of  the  first 
moult,  and  the  perfect  insect  appears  and  takes  to  flight.  Its 
mouth-organs  are  rudimentary  and  it  is  incapable  of  taking  food, 
and  dies  generally  three  or  four  hours  after  its  emergence,  in  this 
brief  space  of  time  having  met  the  other  sex  and  performed  the 
duties  of  reproduction.  Dragon-flies  similarly  lay  their  eggs  in 
water  ;  the  larvae  live  from  one  to  two  years,  and  then,  coming  to 
the  surface,  go  through  metamorphosis.  The  perfect  insects  are 
predaceous  creatures  with  powerful  jaws  ;  they  hawk  and  devour 
smaller  insects,  but  the  total  duration  of  their  adult  life  is  at  most 
a  few  months.  In  many  beetles  the  disproportion  between  the 
duration  of  youth  and  of  the  adult  is  still  more  remarkable.  The 
larvae  of  longicorn  beetles  are  vegetarian,  burrowing  in  the  bark  or 
wood  of-trees.  Mr.  C.  J.  Gahan  has  related  a  remarkable  case  under 
his  own  observation.  In  May  1890  Captain  Ernest  Blunt,  R.E., 
brought  one  of  these  larvae  to  theBritish  Museum.  The  larva  was  in  a 
boot-tree  which  he  had  had  in  use  for  fourteen  years,  seven  of  which 
had  been  spent  in  North -West  India.  The  larva  was  transferred 
to  a  piece  of  beech-wood  forming  part  of  a  museum  stand,  and  lived 
there  until  May  1895,  when  it  was  transferred  to  a  fresh  piece  of 
wood  ;  it  died  shortly  afterwards.  Mr.  Gahan  has  told  me  of 
another  case.  Mr.  Walter  Rose,  of  Ilford,  sent  to  the  Museum  in 
September  1910  the  wooden  base  of  a  bronze  ornament  which  he 
had  had  for  just  five  years.  It  was  one  of  a  pair  given  him,  but  he 
was  unable  to  find  out  where  it  had  come  from.  Two  longicorn 
beetles  of  a  South  European  species  emerged  from  the  wooden 
base  a  day  or  two  after  it  had  been  received  at  the  Museum.  That 
gave  five  years  certain  with  some  unknown  period  in  addition  for 
the  life  of  the  larvae.  The  exact  duration  of  the  life  of  the  adults 
is  not  known,  but  certainly  is  very  much  shorter  than  that  of  the 
larvae,  usually  not  extending  over  the  first  winter  after  emergence. 
A  still  more  extraordinary  case  is  that  of  the  seventeen-year  cicada, 
a  North  American  land  bug.  The  adult  insects  are  heavily  built 
creatures  nearly  an  inch  and  a  quarter  in  length,  with  two  pairs  of 
transparent  wings.  The  mouth -parts  are  imperfect  and  the  creatures 
do  not  feed,  living  only  two  or  three  weeks.  The  eggs  are  laid  in 
slits  cut  in  the  bark  of  trees,  and  the  larvae,  soon  after  hatching, 
burrow  into  the  ground,  where  they  live  on  vegetable  matter.  They 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     57 

grow  slowly,  moulting  five  or  six  times  in  the  first  two  years  of  their 
life.  In  the  seventeenth  year  they  leave  the  ground,  burrowing  up 
through  the  surface  soil  or  through  hard-trodden  paths,  and  after 
hiding  for  a  time  under  stones  and  sticks,  crawl  up  trees,  where  they 
undergo  the  final  moult,  from  which  the  perfect  insect  emerges. 

These  various  cases  of  the  shortening  of  the  adult  life  until  it 
leaves  time  only  for  reproduction  must  be  secondary  adaptations, 
for  it  cannot  be  supposed  that  creatures  with  the  elaborate  structure 
of  winged  insects  could  have  come  into  existence  without  the 
capacity  to  feed,  and  the  extreme  instances  are  connected  by  a 
chain  of  intermediate  forms  with  insects  possessing  a  more  normal 
balance  of  the  periods  of  life.  Winged  insects  have  many  enemies  ; 
they  are  fed  upon  by  all  manner  of  reptiles,  birds  and  mammals. 
Weismann  has  suggested  that  the  pressure  of  the  struggle  for 
existence  is  so  great  that  it  has  become  of  importance  to  them  to 
get  through  the  business  of  reproduction  as  quickly  as  possible,  and 
that  those  insects  have  survived  best  and  so  have  been  favoured 
by  natural  selection  in  which  sexual  maturity  most  quickly  followed 
the  attainment  of  the  adult  form.  In  the  extreme  cases  where  the 
insects  became  capable  of  reproduction  immediately  after  their 
final  moult,  and  where  little  or  no  time  had  to  be  spent  in  choosing 
suitable  places  for  the  eggs,  it  became  unnecessary  for  the  adults 
to  feed,  and  so  their  mouth-organs  degenerated.  This  certainly 
provides  a  reasonable  explanation  as  to  why  the  laying  of  eggs 
should  be  hurried,  for  it  is  plain  that  the  species  would  soon  die 
out  if  most  of  its  adult  members  were  killed  off  before  they  had 
had  time  to  lay  the  foundation  of  the  next  generation.  It  is  a  little 
more  difficult  to  understand,  however,  why  the  insects  should  die 
so  quickly,  even  although  they  have  accomplished  their  task  of 
reproduction.  Weismann  suggested  that  this  too  was  the  result 
of  natural  selection  ;  he  supposed  that  it  was  an  advantage  to  a 
species  to  be  represented  by  as  many  fresh  and  vigorous  forms  as 
possible,  and  that  just  as  a  gardener  removed  faded  flowers  from 
his  floral  borders  and  replaced  them  by  younger  and  more  vigorous 
plants,  so  death  came  to  weed  out  animals  that  had  been  battered 
by  the  accidents  of  life,  as  quickly  as  possible  after  the  maintenance 
of  the  species  had  been  secured  by  reproduction.  He  suggested, 
further,  that  every  animal  was  wound  up,  so  to  speak,  only  to 
live  for  the  time  necessary  to  fulfil  its  cycle  of  life,  and  when 
that  had  elapsed,  the  vital  processes  of  repair  and  of  removal 
of  wasted  tissue  which  must  continue  to  operate  so  long  as  an 


58  CHILDHOOD  OF  ANIMALS 

animal  remains  alive,  ceased.  Other  naturalists  have  supposed 
that  the  business  of  reproduction,  and  especially  the  rapid  formation 
and  deposition  of  great  quantities  of  eggs,  throw  a  fatal  strain  on 
the  insect  and  that  it  dies  of  exhaustion.  Metchnikoff  has  shown 
that  many  insects  appear  to  die  from  a  kind  of  self-poisoning,  or 
from  the  attack  of  some  microbial  parasite,  and  if  this  be  a  usual 
event,  it  is  clear  that  the  process  of  reproduction  should  be  hurried 
on  as  quickly  as  possible,  to  secure  that  it  shall  have  taken  place 
before  the  insect  dies.  What  at  least  is  certain  is  an  association 
between  the  acceleration  of  reproduction  and  the  shortening  of  the 
adult  life.  When  the  next  generation  has  been  provided  for,  the 
adults  have  accomplished  their  mission  in  life  and  are  no  longer 
required.  Whether  they  die  from  exhaustion,  or  because  their 
tissues  have  an  inherently  limited  duration  of  life,  or  because  they 
are  unable  to  resist  the  attacks  of  poisons  from  without  or  from 
within,  may  some  time  be  solved.  To  me  it  seems  most  probable 
that  the  influence  of  natural  selection  has  worked  through  speeding 
up  the  process  of  reproduction,  until  that  occurred  so  quickly  that 
it  almost  certainly  would  have  taken  place  before  the  various 
accidents  from  within  and  from  without  destroyed  the  adult. 
Creatures  subject  to  great  destruction  by  other  animals,  creatures 
that  had  little  powers  of  resistance  to  microbes,  or  that  were  specially 
liable  to  die  because  of  the  inherent  delicacy  of  their  constitutions, 
would  become  extinct  unless  they  reproduced  as  soon  as  possible. 
Among  a  very  large  number  of  different  animals  there  are  wide 
individual  differences  in  the  time  when  sexual  maturity  occurs. 
Stock-breeders  have  taken  advantage  of  this  natural  variability, 
and  have  produced  breeds  which  become  mature  at  unusually  early 
ages  when  the  object  is  to  grow  animals  for  the  table  as  cheaply  as 
possible,  or  breeds  that  mature  later  when  the  object  is  to  secure 
special  strength  and  stamina  ;  and  it  seems  extremely  probable 
that  similar  changes  have  come  about  under  natural  conditions, 
according  to  the  needs  of  the  particular  species.  The  postponement 
of  reproduction  lengthens  the  period  of  youth,  and  gives  a  greater 
opportunity  for  education  before  the  absorbing  responsibilities  of 
adult  life  have  been  assumed.  The  acceleration  of  reproduction 
secures  that  a  species  which  has  many  enemies  should  leave  abundant 
progeny,  although  it  may  actually  lead  to  a  degeneration  of  the 
structure  and  qualities  of  the  adults. 

Among  insects  generally  there  is  a  kind  of  division  of  labour 
between  the  larval  and  the  adult  stages.     In  the  larval  period  the 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     59 

chief  functions  of  the  body  are  feeding  and  growth,  whilst  in  the 
adult  condition  the  chief  function  is  reproduction.  As  we  have 
seen,  this  division  of  labour  may  be  carried  so  far  that  the  adult  is 
incapable  of  feeding.  There  are  some  extraordinary  cases,  how- 
ever, where  reproduction  takes  place  in  the  larval  state,  with  the 
result  that  the  adult  state  is  dropped  altogether.  The  gall-midges 
'are  very  small  two-winged  flies,  the  larvae  of  which  live  on  the 
tissues  of  plants,  sometimes  doing  great  damage,  the  Hessian  fly, 
which  attacks  wheat,  being  a  familiar  example.  The  adult  females 
of  most  of  these  flies  lay  eggs  on  the  plant,  and  these  hatch  out 
iinto  minute  grubs,  which,  after  a  time  of  feeding  and  growing,  pass 
''through  metamorphosis  and  produce  the  adult  winged  insects.  In 
one  or  two  cases,  however,  it  has  been  found  that  the  ovaries  are 
developed  actually  in  the  larvae  and  that  these  produce  young  which 
live  on  the  tissues  of  their  parent  and  finally  leave  it  by  boring  a 
hole  through  the  skin.  The  parent  in  such  a  case  dies  without 
having  become  a  perfect  insect. 

Similar  instances  of  reproduction  before  the  larval  state  has  been 
passed  through  occur  as  rare  exceptions  in  several  groups  of  the 
animal  kingdom,  but  the  best-known  examples  are  found  in  the 
batrachians.  The  youthful  stage  of  most  of  these  animals,  as  I 
have  described  in  Chapter  II,  is  passed  in  water,  the  young  animals 
being  tadpoles.  Usually  the  tadpole  changes  into  the  adult  condi- 
tion long  before  the  approach  of  winter.  It  sometimes  happens, 
however,  that  the  metamorphosis  is  delayed,  and  the  animals, 
growing  far  beyond  the  usual  size,  live  through  winter  in  the 
tadpole  condition.  Such  a  result  has  been  produced  in  a  number 
of  frogs  and  toads,  including  both  the  edible  frog  and  the  common 
grass  frog,  the  common  toad  and  the  South  European  tree-frog,  one 
of  the  methods  adopted  being  to  place  a  grating  below  the  surface 
of  the  water,  so  that  the  tadpoles  cannot  emerge  and  have  no 
access  to  air.  These  cases  are  only  unusual  prolongations  of  the 
duration  of  youth,  and  the  abnormal  tadpoles  eventually  either  die 
or  pass  through  their  metamorphosis  and  become  adult.  In  some 
of  the  urodeles,  those  batrachians  which  retain  the  tail  throughout 
adult  life,  a  further  stage  has  been  observed.  Examples  of  the 
common  newt,  the  Alpine  newt  and  the  crested  newt  have  become 
adult,  and  have  laid  fertile  eggs  which  duly  developed,  before  they 
had  passed  through  metamorphosis  ;  and  there  is  reason  to  believe 
that  such  an  abnormal  state  of  affairs  occurs  as  a  regular  event 
in  a  number  of  instances.  A  celebrated  case  is  that  of  the 


6o 


CHILDHOOD  OF  ANIMALS 


Mexican  axolotl  (Fig.  19).  These  animals  occur  in  large  numbers 
in  lakes  near  Mexico  City,  where  they  form  an  important  article  of 
food.  They  are  dark-coloured,  tadpole-like  creatures  which  when 
fully  grown  are  seven  to  nine  inches  in  length,  and  possess  a  swim- 
ming tail  with  a  fringing  fin  above  and  below,  with  the  usual  two 
pairs  of  limbs  with  fingers  and  toes,  and  with  three  pairs  of  gills 
projecting  from  the  sides  of  the  neck.  They  are  quite  hardy,  and 
are  familiar  objects  in  aquaria  in  Europe,  where  they  breed  freely. 


;v  •  ., 


FIG.  19.     Metamorphosis  of  Axolotl.    Upper  figure,  the  aquatic 
axolotl  ;  lower  figure,  the  terrestrial  amblystoma. 

They  were  supposed  to  belong  to  the  division  of  batrachians  which 
are  known  as  Perennibranchiata,  as  they  retain  their  gills  and  the 
aquatic  habit  throughout  life.  In  1865,  however,  some  young 
axolotls,  bred  in  the  Jardin  des  Plantes  at  Paris,  gradually  lost  the 
gills  and  the  fin  along  the  back  and  tail.  The  gill-slits  closed  up, 
the  head  became  broader,  and  the  animals  left  the  water  perma- 
nently. The  black  skin  became  blotched  with  spots  and  streaks 
of  yellow,  and  it  was  soon  recognised  that  a  metamorphosis  had 
taken  place,  that  the  axolotl  was  not  an  adult  perennibranch,  but 
the  larval  form  of  a  well-known  salamander,  Amblystoma  tigrinum 
(Fig.  19).  A  German  lady,  under  the  direction  of  two  professors 
at  the  University  of  Freiburg,  proceeded  to  make  a  set  of  careful 
experiments,  and  found  that  it  was  possible  to  induce  young  axolotls 


YOUTH  IN  BIRDS  AND  LOWER  ANIMALS     61 

to  change  into  the  adult  amblystomas,  the  most  successful  method 
being  to  keep  them  in  very  shallow  vessels  so  that  they  had  a 
frequent  opportunity  of  breathing  air,  and  at  the  same  time  to  make 
the  normal  gill-respiration  inconvenient  by  securing  that  the  water 
should  have  less  than  its  proper  quantity  of  dissolved  air. 

The  curious  facts  as  to  larval  reproduction  in  the  axolotl  throw  a 
possibly  new  light  upon  the  relations  of  the  different  groups  of 
batrachians  to  each  other.  It  had  been  assumed  that  the  Perenni- 
branchiata,  those  which  remained  aquatic  and  had  gills  throughout 
their  life,  were  the  representatives  of  a  primitive  stock,  a  ad  that  in 
the  same  way  the  gilled  larvae  of  the  terrestrial  adults  represented 
an  ancestral  stage  passed  through  in  the  actual  development  of  the 
modern  forms.  It  is  clear,  however,  that  the  external  gills  do  not 
correspond  with  the  primitive  fish  gills,  and  that  the  limbs  with 
fingers  and  toes  correspond  with  terrestrial  rather  than  aquatic 
conditions.  If  the  occasional  metamorphosis  of  the  axolotl  had 
not  been  discovered,  the  axolotl  would  have  been  classed  with  the 
other  perennibranchs.  It  is  quite  probable  that  the  other  perenni- 
branchs are  creatures  which  have  actually  permanently  lost  their 
terrestrial  adult  condition,  and  so  are  degenerate  rather  than 
primitive.  It  has  been  suggested  even  that  the  ancestors  of  the 
living  batrachians  were  terrestrial  creatures,  breathing  by  lungs 
and  with  two  pairs  of  limbs  with  hands  and  feet  possessing  fingers 
and  toes,  and  that  the  aquatic  larvae  with  their  external  gills  were 
new  interpolations  in  the  life-history.  If  such  a  theory  were 
justified,  then  the  perennibranchs,  instead  of  being  an  ancestral 
set  of  batrachians,  would  really  be  more  modern  than  the  terrestrial 
forms,  and  their  greater  simplicity  would  be  due  to  the  loss  of  the 
adult  stage. 

The  progress  of  evolution  is  not  invariably  associated  with  advance 
in  structure,  and  it  is  quite  possible  that  some  of  the  groups  which 
we  now  think  of  as  being  primitive  and  as  possibly  representing 
ancestral  stages  in  evolution  are  merely  larvae,  to  which  the  power 
of  reproduction  has  been  shifted  backwards,  and  which  in  consequence 
have  permanently  lost  their  adult  stages.  From  this  point  of  view 
the  curiosities  of  youth  which  I  have  been  describing  would  have 
a  great  importance  in  the  theory  of  evolution. 


CHAPTER  V 
COLOUR  AND  PATTERN  IN  ANIMALS 

IT  very  often  happens  that  young  animals,  even,  although  they  may 
closely  resemble  their  parents  in  structure,  wear  liveries  with 
different  colours  and  patterns.  A  full-grown  lion  (see  Plate  III) 
is  nearly  uniformly  brown ;  his  coat  is  rather  paler  on  the 
under  parts,  and  his  mane  and  tail-tuft  may  be  tinged  with  black ; 
and  some  individuals,  especially  lionesses,  may  show  very  faint 
traces  of  spots.  But  lion-cubs  are  spotted  animals.  The  American 
tapir  (Plate  VI,  p.  94)  is  very  dark  in  colour,  almost  black  all  over 
except  for  a  white  line  round  the  edge  of  the  shell  of  the  ear  ;  the 
Malayau  tapir  is  parti-coloured,  the  head,  fore-quarters  and  legs 
being  black,  but  with  a  great  saddle  of  white  covering  the  hinder 
part  of  the  back  and  passing  down  under  the  ventral  surface. 
Young  tapirs  for  the  first  two  or  three  months  of  their  existence 
are  vividly  striped  and  spotted  with  white,  and  the  pattern  of  the 
Malayan  and  the  American  forms  is  almost  identical.  Red  deer 
are  coloured  almost  uniformly  reddish-brown,  except  for  a  light 
patch  or  disc  on  the  rump,  but  the  young  fawns  are  conspicuously 
spotted  (Plate  V,  p.  92).  There  are  few  living  creatures  so  bril- 
liantly coloured  as  the  male  birds-of -paradise.  The  head,  back, 
the  upper  surface  of  the  wings  and  tail  of  the  king  bird-of -paradise, 
for  instance,  are  resplendent  with  a  glow  partly  orange  and  partly 
scarlet,  and  there  is  a  breastplate  of  metallic  green  from  which  a  little 
bunch  of  brown  feathers  tipped  with  green  hangs  down  at  each  side. 
The  chest  and  the  lower  part  of  the  body  are  pure  white,  and  the 
long  plumes  which  project  from  the  tail  terminate  in  shining  tufts 
of  green  rolled  up  so  that  they  resemble  the  eyes  on  the  feathers 
of  a  peacock.  The  upper  parts  of  young  males  are  clothed  with 
sad -coloured  brown,  and  their  chests  and  under  parts  are  banded  and 
mottled  with  a  paler  brown.  Sea-gulls  are  brilliantly  patterned 
birds,  the  general  effect  being  black-and-white,  the  chest  and  under 
parts  being  white,  and  the  head  being  covered  with  a  cape  or 
mantle  of  black  or  dark  grey.  Young  sea-gulls  (see  Plate  VIII,  p.  162) 

62 


PLATE   HI 

LION,  LIONESS  AND  CUB 


Lion  cubs  vary  in  the  extent  to  which  they  are  spotted,  and 
the  example  shown  is  rather  heavily  spotted. 


CH 
^      COLOUR  AND  I 

IT  very  often  happens  that 
resemble    their   par 
rent  colours  and  patterns 
;  early   uniformly   brow 

•  T  parts,  and  his  mane  and 

and  some  individuals,  ^sppffictjl^  ^ 

:.*s  of  spots.     But  lion-cubs  are  spo* 
tapir  (Plate  VI$JJl>  X! 

ayai    fapj, 

being  b;  with  .' 

part  of  the   back  and  pa^ 
s  for  tL 

,jed  ana 
Malayan  and  the  Aim 

coloured  almost  uniformh 
h  or  disc  on  the  rump,  but 
ted  (Plate  V,  p.  92). 
ly  coloured  as  the  ma 
the  upper  surface  of  the  wi 
for  instance,  are  resplendent  w 

let,  and  there  is  a  breas> 
bunch  of  brown  feathers  tip 
The  chest  and  the  lower  par 
;  plumes  which  project 
rolled  up  so  that  tl 

•  peacock.     The  upper 

I  brown,  am; 

mott:  paler  b 

bird 
parts 
mantle  oi 


tp  HI) 

black ; 

• 


ear 


the 

inder 

rface. 

tence 

'f  the 

Red  deer 

light 

ously 

bril- 

'>ack, 

•  disc, 

artly 


and 


with 
1  and 
rned 

and  under 
a  cape  or 
III,  p.  162) 


\ 


\ 


COLOUR  AND  PATTERN  IN  ANIMALS         63 

are  at  first  white,  spotted  with  black  and  brown,  and  then  covered 
with  a  speckled  coat  of  brown,  excessively  unlike  the  conspicuous 
pattern  of  the  adult.  The  king  penguin  (see  Plate  VII,  p.  104)  is 
another  brilliantly  black-and-white  bird,  but  its  head,  neck  and 
the  upper  part  of  the  chest  are  tinged  with  orange  and  yellow.  The 
chick,  even  when  it  is  as  large  as  the  parent,  is  covered  with  a 
fluffy  coat  greyish-brown  all  over.  The  two  sides  of  a  young  sole 
or  flounder  are  alike,  pale  grey  in  colour  and  studded  with  specks 
of  black.  When  the  sole  settles  down  on  its  side  to  its  adult  life 
as  a  fish  that  haunts  the  bottom,  the  side  which  is  going  to  lie  next 
the  sand  of  the  bottom  becomes  almost  pure  white,  whilst  the  other 
darkens  and  becomes  much  more  spotted.  I  shall  give  many  more 
examples  later  on,  but  for  the  present  it  is  enough  to  state  that  a 
difference  in  colour  and  pattern  between  the  young  and  the  adult 
is  extremely  frequent  amongst  animals. 

Colour  and  pattern,  or  the  combined  result  of  colour  and  pattern 
which  is  usually  called  coloration,  are  subjects  that  have  attracted 
the  attention  of  naturalists  from  the  earliest  times,  and  before 
discussing  the  special  cases  of  young  animals  it  will  be  convenient 
to  set  down  some  general  ideas  on  the  matter.  There  is  no  side  of 
zoology  that  has  been  more  fertile  in  producing  theories  ;  many  of 
the  greatest  naturalists,  and  the  lesser  naturalists  almost  without 
exception,  have  written  on  the  subject,  and  I  do  not  doubt  but  that 
every  person  who  will  read  these  lines  has  made  or  will  make 
confident  theories  of  his  own.  I  hope,  therefore,  to  proceed  warily, 
and  to  describe  some  of  the  most  characteristic  facts  rather  than 
to  select  among  the  existing  theories,  or  to  provide  a  new  one. 
I  shall  begin,  however,  by  a  warning,  specially  necessary  in  trying 
to  interpret  coloration.  We  must  not  scrutinise  Nature  too  closely, 
expecting  to  find  a  manifest  purpose  in  all  her  variety.  Reason 
or  cause  there  is  for  everything,  in  the  sense  that  did  we  know  the 
complete  chemical,  physical  and  vital  forces  at  work  in  the  making 
of  any  living  thing,  we  should  know  that  it  must  have  this  or  that 
pattern  and  colour  and  no  other.  But  the  factors  that  have  brought 
coloration  into  existence  are  separate,  and  must  be  studied  separately 
from  the  question  as  to  whether  the  results  are  of  any  use  or  what  that 
use  may  be.  We  must  free  our  minds  from  the  idea  that  there  is  a 
necessary  and  direct  utility  in  everything  we  see.  The  diamond 
takes  no  delight  in  its  own  shining,  and  there  is  no  gain  to  the  ruby 
that  it  glows  with  a  sullen  fire,  or  to  the  opal  that  it  quivers  with 
the  lights  of  the  sea  at  dawn.  The  red  blood  flushes  the  pale  skin 


64  CHILDHOOD  OF  ANIMALS 

of  a  girl  until  it  becomes  a  wonder  and  a  delight,  but  it  ran  no  less 
red  for  countless  generations  under  the  thick  and  hairy  hide  of  the 
apes  that  were  her  ancestors.  The  little  shining  grains  that  we 
call  pearls  are  diseases  of  the  shell-fish  in  which  they  are  formed. 
Undoubtedly  there  is  a  reason  for  it,  but  who  shall  say  that  there 
is  a  purpose  in  the  males  of  the  eclectus  parrots  being  green  whilst 
the  females  are  red  ?  The  truth  is  that  living  things  must  have 
colour  and  pattern  whether  these  be  directly  useful  to  them  or  no. 

Even  the  untrained  eye 
at  once  picks  out  fossils 
in  a  slab  of  rock  or 
shells  lying  on  the  sea- 
shore, and  identifies' 
them  as  having  be- 
longed to  living  things, 
because  their  patterned 
surface  is  in  contrast 
with  the  formless  mono- 
tony of  the  surround- 
ing matter.  Pattern  is 
essentially  repetition  of 
parts.  If  we  stand  in 
a  hall  of  mirrors  and 
look  at  the  endless 
images  of  ourselves  re-' 

FIG.  20.  Repetition  Pattern  obtained  by  tearing  fleeted  from  mirror  to 
holes  in  a  sheet  of  folded  paper  and  then  mirror  We  shall  find 
unfolding  it. 

that     we     and     these 

multiplications  of  our  body  compose  a  pattern.  Similarly  in 
the  scientific  toy  known  as  a  kaleidoscope,  a  few  fragments  of 
coloured  tinsel  and  glass  are  dropped  into  a  cardboard  tube  with 
a  glass  bottom  surrounded  by  a  circle  of  little  mirrors.  When  we1 
look  through  the  tube  against  the  light  the  duplications  and1 
reduplications  of  the  fragments  form  a-n  elaborate  pattern  which 
changes  into  a  new  complexity  as  we  revolve  or  shake  the  tube. 
If  we  take  a  sheet  of  thin  paper  and  fold  it  first  into  two  and  then 
into  four,  then  double  it  diagonally  from  the  central  corner,  then 
tear,  however  roughly,  a  few  holes  in  the  folded  edges,  we  shall 
find  on  unfolding  it  again  that  we  have  formed  a  symmetrical 
pattern,  radiating  from  the  centre  of  the  sheet  (Fig.  20).  If  we 
take  another  sheet  of  paper,  fold  it  across  so  as  to  make  a  guiding 


COLOUR  AND  PATTERN  IN  ANIMALS         65 

crease  along  the  middle,  and  then  unfolding  it,  write  a  name  in  ink 
with  a  thick  pen  along  one  side  of  the  crease,  then  quickly  fold  it 
over  and  press  it  down  before  the  ink  has  dried,  we  shall  find  we 
(have  made  another  kind  of  pattern  (Fig.  21),  this  time  not 
^radially  symmetrical  round  a  central  point,  but  bilaterally 
symmetrical  on  the  two  sides  of  the  crease,  and  more  complicated 
in  detail  because  of  the  different  thicknesses  of  the  ink  we  left  to  be 
doubled  and  the  unconsciously  different 
pressures  we  gave  when  folding  over  the 
paper  on  the  wet  ink. 

The  growth  of  every  body  takes  place  by 
the  multiplication  of  the  little  units  we 
know  as  cells,  or  of  higher  units  composed 
of  masses  of  cells.  Sometimes  the  multi- 
plication takes  place  radially  and  regularly, 
or  radially  and  irregularly,  sometimes  in  a 
bilateral  plane,  and  this  again  regularly  or 
irregularly.  And  so  all  the  tissues  of  the 
body,  microscopic  or  visible  to  the  naked 
eye,  are  patterned.  In  the  simpler  forms  of 
life  and  the  simpler,  most  mechanical  parts 
of  the  body,  the  patterns  are  simple  and 
regular,  to  whatever  system  they  may  belong. 
In  the  higher  tissues  and  higher  organisms 
the  primitive  numerical  symmetries  of  re-  FIG.  21.  Bilateral  Pattern 
petition  are  disguised  by  ordered  irregu-  han^writin7  ^theStual 
larities  in  growth,  now  one  part,  now  another  words  written  a  were 
part  being  retarded  or  accelerated,  and  by  '  R°yal  institution." 
the  interference  of  the  growth-forces  of  one  set  of  organs  with  the 
,growth-forces  of  another.  If  a  drop  of  some  oily  pigment  be  placed 
on  water  in  a  bowl  it  will  spread  out  slowly  in  a  ring-shaped  pattern  ; 
if  other  drops  be  placed  near  it,  as  they  spread  they  will  interfere  with 
and  distort  the  patterns  already  formed.  If  the  water  be  made  to 
move  slowly  by  stroking  the  surface  with  a  brush  or  by  blowing  on  it, 
the  systems  of  rings  will  spread  out  into  irregular  curved  streaks, 
forming  the  well-known  watered  or  moire  effects  used  in  textiles, 
and  sometimes  seen  on  the  paper  lining  the  covers  of  books.  Similar 
patterns  are  very  common  in  animal  tissues,  due  to  the  growth- 
forces  being  more  intense  in  one  direction  than  in  another.  Thus 
in  a  multitude  of  ways  patterns  are  formed  in  the  tissues  of  animals, 
as  the  inevitable  consequence  of  structure  and  mode  of  growth,  and 

c.A.  E 


66  CHILDHOOD  OF  ANIMALS 

the  pattern,  although  inevitable  and  associated  with  structure 
that  no  doubt  is  useful,  is  not  in  itself  useful.  We  do  not  frame 
explanations  of  its  meaning  and  purpose  when  it  is  concealed 
within  the  body  and  made  visible  only  by  dissection  and  the  micro- 
scope, but  if  it  crop  out  on  the  surface  and  so  is  visible,  then  we 
are  disposed  to  imagine  that  it  must  have  some  special  fitness  for 
the  conditions  in  which  the  animal  lives,  and  to  speculate  as  to 
how  the  conditions  could  have  called  into  existence  the  pattern 
that  fitted  them.  I  do  not  doubt  that  such  inevitable  growth- 
patterns  sometimes  confer  an  advantage  on  an  animal,  and  have 
been  maintained  by  the  operation  of  natural  selection,  but  it  appears 
to  me  that  it  is  their  absence  and  not  their  presence  that  requires 
explanation,  and  that  natural  selection  has  been  more  effective  in 
smoothing  out  and  obliterating  the  inevitable  growth-patterns  than 
in  preserving  them,  or  being  the  agent  in  their  formation. 

All  visible  things  must  have  colour,  and  so  also  it  is  inevitable 
that  animals  must  have  colour.  The  colour  may  be  due  to  one  of 
several  causes  or  to  a  combination  of  causes.  Many  hues,  especially 
those  with  metallic  sheen,  depend  on  the  structure  of  the  surface 
on  which  the  light  falls,  the  white  light  being  broken  up  in  the 
process  of  reflection.  When  a  piece  of  transparent  glass  or  ice  is 
powdered  it  becomes  white  like  snow,  and  this  appearance  is  due 
to  the  total  reflection  of  the  light  from  the  mixture  of  little  solid 
particles  and  intervening  bubbles  of  air.  The  white  of  animal 
tissues  is  produced  in  this  way.  The  fur  and  feathers  of  arctic 
mammals  and  birds,  white  patches  on  the  skin  and  so  forth  come 
about  because  there  are  little  bubbles  of  air  or  of  some  other  gas 
entangled  in  the  structure  of  the  tissue.  The  blues  and  greens  of 
many  birds  and  insects  which  do  not  change  in  colour  according 
to  the  angle  at  which  light  is  reflected  from  them,  and  the  still 
more  vivid  metallic  iridescent  colours  which  change  as  they  are 
moved  about,  and  which  are  conspicuous  in  the  eyes  of  the  peacock's 
tail  and  in  the  bright  tints  of  birds-of -paradise,  are  due  to  a  combina- 
tion of  structure  and  pigment.  Frequently  there  is  a  dark  pigment 
underlying  a  transparent  layer,  forming  a  kind  of  mirror,  and  the 
play  of  colours  comes  from  the  varying  incidence  of  light  and  the 
varied  sculpturing  or  thickness  of  the  transparent  layer. 

Other  colours  may  be  due  to  the  presence  of  pigments — that  is 
to  say,  actually  coloured  substances.  Blues  and  greens  occasion- 
ally, reds,  yellows,  blacks  and  browns  almost  invariably  are 
pigmentary.  The  brilliant  crimson  of  the  feathers  of  the  turacos  is 


COLOUR  AND  PATTERN  IN  ANIMALS         67 

not  only  a  pigment,  but  one  that  is  soluble  in  soft  water,  and  is 
washed  out  in  a  heavy  shower  of  rain.  A  less  well  known  case  is 
that  of  the  black  colour  of  the  Malay  tapir.  If  the  hand  be  rubbed 
over  the  dark  portion  of  the  body  a  black,  greasy  stain  comes  off, 
whilst  the  grey  part  of  the  body  is  devoid  of  this  secretion.  In 
some  of  these  cases,  perhaps  in  most  of  them,  the  pigment  has  a 
direct  physiological  importance,  as,  for  instance,  the  red  colour  of 
blood,  due  to  the  presence  of  haemoglobin,  the  substance  which 
carries  oxygen  to  the  tissues  ;  or  some  of  the  greens  and  yellows, 
which  are  products  of  the  chemical  changes  of  the  body,  and  are 
waste  matters  on  the  way  to  be  removed ;  or  blacks,  which  also 
not  infrequently  are  products  of  excretion.  I  have  already  said 
that  the  blood  was  red  long  before  the  colour  became  a  visible 
ornament  of  the  body.  So  also  the  black  lining  of  the  body-cavity 
in  many  reptiles,  the  brilliant  greens  and  golden  yellows  of  the 
gall-bladder,  the  vivid  green  of  the  bones  of  fishes  like  the  South 
American  lung-fish,  are  clear  instances  of  strongly  marked  colour, 
for  which,  were  they  visible  externally,  we  should  attempt  to 
find  an  adaptive  explanation,  to  interpret  in  the  light  of  suitability 
to  the  surrounding  conditions.  Precisely  as  in  the  case  of  pattern, 
we  must  not  be  too  certain  that  colour  has  a  direct  purpose.  Colours 
may  be  useful,  and  often  are  turned  to  use,  but  their  utility  may 
only  be  secondary,  a  laying  hold  of  something  that  was  already 
there.  All  warm-blooded  animals  radiate  out  heat,  varying  in 
amount  with  the  physical  activities  of  their  bodies,  with  the 
structure  and  disposition  of  their  protective  coverings  and  so  forth, 
and  if  we  possessed  organs  as  sensitive  to  heat  as  our  eyes  are  sensi- 
tive to  colour  and  light,  we  should  learn  to  recognise  the  presence 
and  perhaps  the  nature  of  animals  near  us  by  means  of  the  messages 
that  such  a  heat-sense  would  convey  to  the  brain,  and  the  heat 
diffusion  of  the  animals  themselves  might  have  been  turned  to 
account  for  their  own  purposes.  When  small  birds  are  roosting 
in  the  open  air  on  a  cold  night  they  fluff  out  their  feathers  until 
the  bodies  become  almost  globular,  and  by  so  doing  they  retain 
more  of  their  internal  heat.  In  such  a  condition  they  would  be 
unnoticed  by  a  heat-sense  at  a  much  greater  distance.  They  are  thus 
accidentally  protected  against  a  danger  that  does  not  exist.  And 
so  it  may  be  with  some  of  the  colours  of  animals. 

Finally,  the  presence  of  colour,  whether  it  be  due  to  structure  or 
to  pigment,  makes  pattern  more  conspicuous,  while  the  existence 
of  pattern  calls  attention  to  differences  of  colour.  When  micro- 


68  CHILDHOOD  OF  ANIMALS 

scopists  are  examining  the  structure  of  animal  tissues,  one  of  their 
difficulties  is  that  the  pale  grey  tone  of  the  material  they  are  investi- 
gating is  almost  uniform.  And  so  they  have  learned  to  treat  it 
with  various  dyes,  some  of  which  make  the  differences  in  structure 
visible  merely  because  certain  parts  stain  more  deeply  than  other 
parts,  whilst  invisible  chemical  differences  become  visible  by  the 
parts  of  the  tissue  accepting,  refusing  or  changing  the  colour  with 
which  they  are  bathed.  And  as  the  red  blood  shining  through  the 
pale  skin  suffuses  the  surface  with  tints  of  different  intensity,  so 
the  pigments  which  are  being  excreted  through  the  skin  become 
differently  entangled  in  different  parts  of  the  structure,  make  new 
combinations  of  colour  chemically  or  physically,  and  the  varied 
structure  itself  shines  differently  under  the  same  beams  of  light. 

Colour,  pattern,  and  the  combination  of  colour  and  pattern  that 
we  call  coloration  are  to  be  expected  everywhere  in  the  animal 
kingdom,  as  indeed  in  the  living  world.  They  are  the  visible 
expression  of  the  complex  nature  and  of  the  mode  of  growth  of 
living  things.  All  organisms  increase  in  size  by  the  multiplication 
of  parts,  and  the  simpler  they  are  the  more  mechanically  geometrical 
we  must  expect  them  to  be.  As  they  become  more  complex  in 
structure,  the  primitive  and  yet  more  startling  symmetry  of  their 
patterns  becomes  altered  by  irregular  growth,  by  excess  in  some 
parts,  retardation  in  others,  and  by  interference  of  the  growth  of 
different  systems  or  centres.  Structurally  every  body  is  a  mosaic, 
but  it  is  a  mosaic  which  has  grown  by  the  growth  and  multiplication 
of  the  separate  pieces  at  different  rates.  It  must  have  pattern. 
The  different  pieces  and  systems  of  pieces  must  have  colour,  and  as 
they  become  different  in  their  functions,  inherent  differences  in 
colour,  and  differences  due  to  different  reactions  to  the  coloured 
fluids  and  substances  that  pervade  the  whole,  cause  a  still  greater 
diversity.  And  so  coloration  is  an  inevitable  outcrop,  which  may 
or  may  not  be  useful. 

And  now,  having  fenced  the  tables,  we  pass  to  consideration  of 
the  uses  to  which  colours  and  patterns  may  be  put  and  of  the  ad- 
vantages they  may  confer  on  their  owners,  with  a  clear  conscience. 

In  natural  history  all  general  rules  are  dangerous,  but  there  is 
none  safer  than  that  it  is  seldom  an  advantage  to  an  animal  to  be 
conspicuous.  It  is  a  hungry  world,  and  there  is  nothing  more 
generally  useful  than  not  to  attract  attention.  The  lowest  grade  in 
the  evolution  of  coloration  is  when  pattern  that  is  the  direct 
expression  of  structure  and  colour — that  is  to  say,  the  direct  result 


PLATE  IV 

LADY  AMHERST'S  PHEASANTS 

Cock,  hen  and  chicks.  The  drawing  is  not  an  exact  colour 
diagram  of  the  species,  but  gives  the  general  effect  of  the 
coloration,  and  the  contrasted  patterns  of  the  sexes  and 
the  young. 


*:    ..:  A.  i1 

their 
le  grey  t 

,t  uiiifon  -t  it 

.  .• , 

ertain  j- 
»le  chemica; 
ie  accepting,  TL 

are  bathed.     And  the 

i  suffuses  the  surf; 
rients  which  ar< 

differently  entangled  in  -:ake  ftew 

•binations  of  colour  ried 

•cture  itself  shines  <i        VI 

2TM3HMA  YOAJ 

kingdomplco  ioBxddfididb  8i  aniwnh  odT     .MM',  brr«  n-jif  .ifooD 

expresffffc1^^0^!^  ^l^ffffl  '^1  eovrg  tud  .aoiDaqs  9ffj  ],,  miiipL-ib 

living  mfiSp?08^^0  S^^jW^^ff^  9^  i>n«  .not^toloo 

of  parts,  and  the  simpler  th  '*nu^<-  * 

we  must  expect  them  to  x  in 

structure,  the  primitive  and  yet  ir  of  their 

patterns  becomes  altered  by  irreg  in  some 

parts,  retardation  in  others,  and  1  ce  of  the  growth  of 

different  systems  or  centres,     s 

but  it  is  a  mosaic  which  has  grov  plication 

of  the  separate  pieces  at  different  'ern. 

The  different  pieces  and  systeir-  ?d  as 

they  become  different  in  ' 

colour,  and  differences  due 

fluids  and  substances  that  ater 

diversity.     And  so  colorat;  lay 

or  may  not  be  useful.  ' 

And  now,  having  fenced  i  of 

the  uses  to  which  colou  ad- 

vantages they  may  con 

In  natural  history  there  is 

none  safer  than  that  it  rial  to  be 

jus.     It  is  a  hung  -  <g  more 

orally  useful  than  not  t<  •:  grade  in 

;e  direct 
direct  result 


UOTE 


COLOUR  AND  PATTERN  IN  ANIMALS         69 

of  the  chemical  processes  of  the  body — is  retained.  This  grade  is  to 
be  expected  in  primitive  animals  and  in  the  young  stages  of  animals, 
and,  whether  it  be  brilliant  or  dull,  is  retained  in  higher  types  when 
it  is  not  disadvantageous.  The  second  grade  is  the  smoothing  over 
and  partial  obliteration  of  growth-pattern  and  the  toning  down  of 
natural  colours.  This  condition  is  the  simplest  mode  of  producing 
concealment  by  inconspicuousness,  in  conditions  where  the  first 
grades  of  colour  and  pattern  are  disadvantageous.  The  third  and 
highest  grade  is  when  the  structural  pattern  is  overlaid  by  a  new 
pattern,  often  with  very  little  relation  to  the  natural  growth  and 
symmetry  of  the  animal,  and  where  the  colours  do  not  appear  to 
be  the  direct  result  of  the  ordinary  physiological  processes  of  the 
body.  This  third  grade  is  found  in  the  higher  groups  of  animals,  and 
is  more  frequent  in  adults  than  in  the  young,  and  in  males  than  in 
females.  As  we  shall  see,  even  although  it  may  be  vivid  and  brilliant, 
it  may  yet  secure  inconspicuousness  in  the  natural  environment  of 
the  animals.  These  three  grades  must  be  taken  as  a  help  to  remember 
and  understand  coloration,  and  not  as  an  absolute  set  of  divisions 
into  which  the  facts  fall,  or  into  one  of  which  any  particular  fact  can 
be  placed  with  complete  certainty. 

As  the  cases  in  which  it  appears  to  be  an  advantage  to  animals  to 
be  conspicuous  are  relatively  few,  I  shall  begin  with  them.  Many 
animals,  and  especially  males,  wear  their  bravest  livery  as  a  marriage 
dress,  and  however  they  may  be  coloured  at  other  times,  are 
resplendent  at  the  approach  of  the  breeding  season.  Differences 
in  coloration  of  the  sexes  are  not  frequent  amongst  mammals, 
although  the  males  are  more  usually  distinguished  by  their  powerful 
weapons  of  aggression.  But  the  coloured  patches  on  the  skin 
in  many  monkeys  are  brighter  and  more  conspicuous  in  males, 
and  differences  in  colour  and  pattern  mark  the  males  of  many 
deer,  antelopes  and  small  carnivores.  These  male  ornaments 
are  usually  intensified  during  the  breeding  season.  In  birds 
such  differences  are  almost  the  rule,  and  are  directly  associated 
with  the  breeding  season,  which  in  many  cases  is  preceded  by 
a  moult,  after  which  the  sexual  plumage  is  assumed,  or  the  colour 
of  the  naked  parts  intensified.  Every  one  knows  that  the 
cocks  are  most  highly  ornamented  in  such  familiar  examples 
as  the  fowls  and  pheasants  (see  Plate  IV),  the  peacocks,  drakes, 
male  ostriches,  birds-of-paradise,  and  so  on.  But  there  are  also 
birds  in  which  the  sexes  are  so  much  alike  that  it  is  almost 
impossible  to  distinguish  them  except  by  observation  of  their 


70  CHILDHOOD  OF  ANIMALS 

habits,  as  in  the  case  of  pigeons,  partridges,  most  parrots,  owls, 
birds-of-prey,  and  many  of  the  small  singing  birds.  There  are  even 
a  few  odd  cases  where  there  is  a  conspicuous  difference  in  colora- 
tion and  the  females  are  the  more  resplendent.  This  happens  in 
phalaropes,  some  but  ton -quails,  painted  snipes  and  cassowaries,  and 
it  is  curious  that  in  these  cases  the  usual  disposition  of  the  sexes 
is  reversed,  and  the  females  are  pugnacious,  aggressive  and  courtiers 
of  the  males.  The  sexes  are  usually  alike  in  reptiles,  but  male 
lizards  may  be  brightly  coloured  when  the  breeding  season 
approaches.  Amongst  batrachians  there  are  many  in  which  the 
sexes  are  alike,  but  male  newts  assume  a  brilliant  nuptial  colora- 
tion. Whilst  the  males  and  females  of  most  fishes  are  alike  in 
colour,  there  are  many  well-known  examples  of  males  becoming 
more  brilliant  in  the  breeding  season.  Butterflies,  moths,  beetles 
and  bugs,  and  dragon-flies  may  be  clad  in  sober  or  gaudy  tints,  and 
are  frequently  alike  in  the  two  sexes,  but  where  there  is  a  difference 
it  is  almost  invariably  the  male  sex  that  is  conspicuous.  In  spiders, 
again,  the  males  are  not  infrequently  more  brightly  coloured  than 
their  mates.  The  interpretation  of  such  sexual  coloration  is  very 
difficult.  In  some  cases,  especially  those  of  insects  where  the 
sexes  are  alike,  bright  colours  belong  to  some  other  category  of 
coloration,  or,  as  Darwin  suggested,  may  have  been  acquired  in 
one  sex  and  then  transmitted  by  inheritance  to  both  sexes.  In 
other  cases  they  may  be  the  mere  expression  of  exuberant  vitality, 
of  active  physiological  processes,  and  may  be  of  no  special  utility 
so  far  as  the  attraction  of  the  sexes  is  concerned,  but  may  have 
been  retained  in  the  brilliantly  coloured  males  because  their  presence 
was  not  disadvantageous,  and  suppressed  in  the  dull  females  where 
it  was  of  advantage  to  the  next  generation  that  the  female  should 
be  inconspicuous  during  her  laying  of  the  eggs  and  guardianship  of 
the  young.  But  there  remain  a  large  number  of  cases  where  one 
sex,  almost  invariably  the  male,  is  always  conspicuous  during  the 
breeding  season,  whether  that  occupy  the  whole  adult  life  or  be  a 
recurrent  episode.  In  such  cases  it  certainly  seems  to  be  an  advan- 
tage to  the  male  to  be  conspicuous,  and  there  is  no  better  interpreta- 
tion of  these  facts  than  that  given  more  than  forty  years  ago,  with 
the  most  judicial  reticence,  by  Charles  Darwin  in  the  "  Descent  of 
Man  and  Selection  in  Relation  to  Sex."  Darwin  showed  that 
in  very  many  cases  where  the  males  were  conspicuously  coloured, 
they  flaunted  their  colours  and  patterns  before  the  female,  excited 
her  attention  by  them,  and  gave  her  the  opportunity,  consciously 


COLOUR  AND  PATTERN  IN  ANIMALS         71 

or  unconsciously,  of  preferring  the  most  vividly  marked.  Sexual 
conspicuousness,  however,  is  a  subject  which  does  not  specially 
concern  young  animals,  and  it  would  be  outside  the  purpose  of 
this  book  to  discuss  the  theory  of  it  at  length.  But  it  is  interesting 
to  notice  that  where  adult  males  are  specially  conspicuous,  so  differing 
from  young  males  and  females,  the  latter  usually  resemble  each 
other  and  together  resemble  more  primitive  forms.  This  seems 
to  suggest  that  the  sexual  coloration  is  an  instance  of  my  third 
grade  of  coloration,  and  is  a  relatively  late  acquisition,  a  thing 
imposed  on  the  more  primitive  patterns  and  colours.  It  is  to  be 
noticed  also  that  in  a  great  many  cases  sexual  coloration  does  not 
conform  with  the  growth  and  structural  lines  of  the  body,  but  has 
much  of  the  character  of  an  artificial  addition. 

It  is  quite  possible  that  females  may  not  exercise  a  conscious 
preference  in  favour  of  conspicuous  males,  and  that  none  the  less 
the  conspicuous  pattern  is  of  advantage  in  attracting  her  attention. 
The  sexes  find  each  other  in  many  ways  :  by  call- notes,  by  scents, 
by  coloration.  I  have  been  watching  this  afternoon  the  familiar 
display  of  the  males  of  two  of  the  beautifully  coloured  pheasants. 
The  Peacock  pheasant  kept  strutting  round  to  face  the  hen,  and 
then  stopped  in  front  of  her,  hiding  his  dull-coloured  breast  but 
showing  the  white  tuft  that  hangs  over  his  forehead  in  the  breeding 
season,  raising  and  expanding  the  wings  with  their  rows  of  blue 
"  eyes,"  and  holding  the  tail  erect  and  expanded,  with  the  rows  of 
large  green  eyes  shining  in  the  sun  so  that  the  whole  bird  was  a 
gorgeous  mass  of  spangles.  The  Amherst  cock  ran  round  the  hen, 
exhibiting  himself  sideways,  raising  the  wing  farthest  from  her, 
depressing  the  one  nearest  her,  and  twisting  the  tail  sideways  so  as 
to  show  the  greatest  part  of  its  coloured  upper  surface.  The  hens 
in  both  cases  were  at  first  indifferent  or  reluctant,  but  the  glittering 
expanses  of  feathers  soon  excited  their  attention.  So  also  brightly 
coloured  male  butterflies  mob  a  female,  fluttering  round  her  and 
showing  off  to  the  best  advantage ;  whilst  male  spiders  dance  in 
front  of  the  females  in  such  a  fashion  as  to  show  off  their  colours. 
Even  if  such  decorations  are  no  more  than  outcrops  of  structure  and 
surplus  physiological  activity,  they  are  used  to  attract  the  attention 
of  the  females  and  possibly  to  excite  them. 

Conspicuous  patches  of  colour,  like  sounds  and  scents,  may  be 
useful  as  recognition  marks,  especially  amongst  gregarious  animals, 
or  where  the  young  follow  the  mother.  Notable  instances  are  the 
yellow  or  white  patches  on  the  rumps  of  many  deer  and  antelopes, 


72  CHILDHOOD  OF  ANIMALS 

which  stand  out  conspicuously  against  the  general  brown  coloration 
of  the  body ;  whilst  the  white,  erect  tails  of  rabbits  and  other 
small  creatures  that  run  in  single  file  in  the  dusk  along  special 
tracks  may  well  serve  as  moving  sign -posts. 

The  most  common  case  of  the  utility  of  conspicuous  coloration 
is  when  that  serves  to  advertise  an  animal  to  its  enemies,  so  that 
it  may  be  easily  seen,  easily  remembered  and  avoided  in  future. 
It  is  plain  that  such  an  advertisement  is  of  little  use  unless  it  be 
associated  with  the  existence  of  an  unpleasant  or  dangerous  property, 
such  as  nasty  flavour,  bad  odour,  power  of  stinging  or  of  giving 
poisonous  bites.  The  advantage  is  either  to  the  individual  animal  or 
to  the  species,  or  to  both.  It  is  useless  for  a  snake  to  have  to  strike 
its  poison-fangs  into  an  animal  that  is  too  big  for  it  to  eat ;  it  is 
worse  than  useless,  for  the  process  exhausts  the  poison  glands 
temporarily  and  puts  them  out  of  action  so  that  they  cannot  be 
used  for  some  time  for  the  purposes  of  the  snake,  whilst  there  is 
always  a  chance  of  the  snake  itself  being  killed  and  eaten  by  its 
prey.  And  so  bright  colours,  terrifying  attitudes  and  noises,  such 
as  hissing  and  rattling,  are  useful  to  the  snake.  Warning  colours 
are  still  more  useful  in  the  case  of  bees  where  the  sting  is  left  in 
the  wound  and  its  loss  kills  the  bee.  Very  many  small  animals 
with  evil  odours,  such  as  skunks,  have  patterns  of  vivid  black  and 
white  which  are  specially  visible  in  the  dusk,  and  it  is  supposed 
that  they  can  thus  be  recognised  by  carnivorous  animals  that 
otherwise  would  kill  them  and  then  find  themselves  unable  to  eat 
them.  No  doubt  a  few  individuals  would  perish  each  season 
whilst  young  carnivores  were  learning  the  lesson  that  such  animals 
were  not  worth  the  trouble  of  killing,  but  the  species  would  gain. 

Opinions  differ  widely  as  to  the  closeness  of  relation  between, 
unpalatability  and  bright  colours  amongst  insects,  but  after  reading 
through  a  considerable  part  of  the  very  extensive  and  rather 
pugnacious  literature  on  the  subject,  I  think  there  is  a  strong 
balance  of  evidence  in  favour  of  the  view  first  suggested  by 
A.  R.  Wallace  to  Darwin,  that  adult  insects  and  caterpillars  which 
insectivorous  birds  and  lizards  find  nauseous  are  extremely  often 
brightly  coloured  and  conspicuously  marked.  Some  of  the  most 
striking  negative  experiments  have  been  made  on  birds  and  reptiles 
in  captivity,  and  as  these  are  frequently  tame  and  accustomed  to 
take  any  food  that  is  offered  to  them,  it  is  not  surprising  that  they 
have  been  found  to  eat  insects  that  are  probably  nauseous.  Such 
negative  evidence  is  more  than  outweighed  by  the  cases  where 


COLOUR  AND  PATTERN  IN  ANIMALS         73 

they  have  either  completely  refused  the  subjects  of  experiment  or 
rejected  them  after  tasting  ;  whilst  the  fact  that  brightly  coloured 
insects  and  caterpillars  in  their  native  haunts  very  seldom  conceal 
themselves  is  a  cogent  argument  for  the  view  that  they  are  un- 
palatable. It  has  been  found,  moreover,  that  young  birds — and 
no  doubt  the  same  is  true  of  young  lizards — have  no  instinctive 
knowledge  of  which  insects  are  not  good  to  eat,  and  that  they  have 
to  learn  by  experiment.  Such  experimental  tasting  must  be 
disastrous  to  the  individual  subjected  to  it,  but  as  insects  and  their 
caterpillars  usually  occur  in  great  numbers  at  a  time,  the  species 
gains,  although  some  of  its  individual  members  perish. 

Other  cases  of  the  possible  utility  of  bright  colour  and  conspicuous 
pattern  are  grouped  under  the  theory  of  mimicry.  It  is  certainly 
true  that  some  animals  without  unpleasant  qualities  resemble  very 
closely,  in  their  appearance  and  ostentatious  habits,  other  animals 
living  in  the  same  locality  which  have  both  conspicuous  coloration 
and  some  quality  the  possession  of  which  it  is  useful  to  advertise. 
The  genuinely  unpleasant  creature  is  called  the  model,  and  the 
creature  resembling  it  is  called  the  mimic,  and  it  was  supposed  by 
H.  W.  Bates,  who  first  suggested  this  explanation,  that  the  imitation 
of  the  model  by  the  mimic  was  useful  to  the  latter  by  deceiving  its 
enemies  into  the  belief  that  they  had  to  deal  with  an  animal 
better  left  alone.  The  most  probable  examples  occur  amongst 
insects.  Ants,  because  of  their  ferocity  and  their  power  of  defence 
and  aggression  by  means  of  their  biting  jaws  and  venomous  stings, 
are  very  generally  left  alone  by  other  members  of  the  animal  kingdom, 
and  are  frequently  closely  imitated  by  harmless  beetles  and  bugs. 
The  stinging  bees  and  wasps  are  similarly  imitated  in  coloration 
and  pattern  by  harmless  flies.  Manv  tropical  butterflies  and  moths 
that  are  known  to  be  distasteful  are  brightly  coloured  and  show  by 
their  habits  and  slow  flight  that  it  is  not  necessary  for  them  to 
avoid  attracting  attention.  They  are  closely  mimicked  by  other 
butterflies  and  moths  that  are  not  distasteful. 

It  is  plain  that  if  such  mimicry  really  bear  the  interpretation  that 
has  been  placed  upon  it,  it  can  be  effective  only  when  the  mimics 
are  less  numerous  than  the  models.  Otherwise,  in  the  process  of 
the  experiments  of  young  birds  and  other  insectivorous  creatures, 
the  lesson  would  be  spoiled  if  the  brightly  coloured  creatures  were 
as  often  harmless  or  tasty  as  otherwise.  F.  Miiller  extended  the 
theory  of  mimicry  to  cover  a  further  set  of  observations.  He 
showed  that  frequently  a  number  of  different  species  or  kinds  of 


74  CHILDHOOD  OF  ANIMALS 

armed  or  nauseous  creatures  inhabiting  the  same  district  were  not 
only  conspicuously  coloured,  but  resembled  one  another  in  the  kind 
of  coloration.  Obviously,  in  mimicry  of  this  kind,  there  would  be 
very  great  economy,  as  each  species  of  the  group  forming  the 
community  of  similarly  coloured  creatures  would  profit  by  the 
lessons  learned  by  tasting  experiments  made  on  individuals  of  any 
of  the  species.  Thus  the  experimental  death-rate,  the  toll  paid  by 
the  whole  community,  would  fall  less  heavily  than  if  it  were  limited! 
to  a  single  species  ;  whilst  the  local  enemies  would  have  to  learn  to 
avoid  only  one  pattern  instead  of  many  patterns. 

The  theory  of  warning  coloration  and  the  associated  theories  of 
mimicry  have  been  attacked  partly  on  the  ground  that  there  is 
not  enough  experimental  evidence  to  justify  them,  and  partly  on 
the  ground  that  the  pattern  and  colour  can  be  explained  otherwise. 
On  the  whole  there  seems  to  be  enough  experimental  evidence  to 
justify  the  conclusion  that  there  is  a  frequent  association  between 
conspicuous  coloration  and  unpleasant  qualities  on  the  part  of 
the  models.  It  is,  however,  another  matter  to  assume  that  the 
coloration  of  the  models  or  mimics  has  come  into  existence  because 
of  its  utility.  The  colours  and  patterns  may  be  the  natural  out- 
crop of  the  constitutions  and  modes  of  growth  of  tjie  creatures  in 
which  they  are  found  ;  and  if  this  be  so,  if  in  fact  they  belong  to 
what  I  have  described  as  the  lowest  grade  of  ornamentation,  it  is 
not  surprising  that  they  should  occur  in  closely  similar  forms  in 
closely  allied  species.  The  recent  experiments  in  breeding  conducted 
by  naturalists  who  have  been  working  on  the  lines  suggested  by 
Mendel  would  seem  to  show  that  even  very  elaborate  coloration 
and  extremely  intricate  patterns  are  produced  inevitably  in  the 
laboratory  of  the  living  organism.  If  this  be  so,  the  path  is  made 
easier,  and  not  more  difficult,  as  some  of  Mendel's  disciples  appear 
to  think,  for  those  who  wish  to  interpret  colour  and  pattern  in 
terms  of  utility.  It  would  no  longer  be  necessary  to  try  to  imagine 
an  increasing  utility  with  each  small  elaboration  of  pattern.  The 
coloration  would  be  produced,  so  to  speak,  ready  made,  and  would 
be  retained  if  it  were  useful,  or  perish  with  its  owner  if  it  were  harmful. 

There  is  no  quality  more  generally  useful  to  an  animal  than  that  of 
being  inconspicuous.  The  living  world  is  a  very  serious  game  of  hide- 
and-seek,  in  which  nearly  every  adult  animal  and  those  young  ones 
that  are  not  hidden  or  protected  by  their  parent  must  join.  The 
penalties  are  severe ;  those  that  are  caught  are  eaten,  and  those  that 
fail  to  catch  starve.  Animals  may  hunt  their  prey  by  scent,  but 


COLOUR  AND  PATTERN  IN  ANIMALS         75 

there  nearly  always  comes  a  critical  final  moment,  when  they  must 
be  able  to  see  the  object  on  which  they  are  to  pounce.  Animals 
may  escape  by  swiftness,  but  it  is  extremely  useful  if  they  are 
so  invisible  that  their  enemy  cannot  easily  follow  them  by 
sight,  and  still  more  useful  if  when  they  are  hard  pressed,  or 
when  they  have  reached  a  favourable  spot,  they  can  suddenly 
fade  into  the  background  and  become  invisible.  We  all  know 
how  difficult  it  is  to  see  animals  in  a  wood,  or  a  heath,  or  on  the 
open  plain,  even  when  they  are  abundant ;  in  chasing  an  animal 
with  net,  or  gun,  or  camera,  we  have  all  been  baffled  by  the  sudden 
and  almost  incomprehensible  disappearance  of  our  quarry.  We 
are  not  surprised  at  the  invisibility  of  animals  with  subdued 
coloration,  or  animals  clearly  like  their  natural  background,  as,  for 
instance,  a  mottled-brown  moth  flat  against  the  bark  of  a  tree,  or  a 
green  caterpillar  lying  on  a  green  leaf,  and  it  is  to  such  obvious 
harmonies  between  coloration  and  environment  that  the  name  of  pro- 
tective coloration  has  been  given.  But  Mr.  Abbott  Thayer  has  shown 
so  many  instances  where  coloration  that  seems  to  us  brilliant  and 
conspicuous  really  serves  for  concealment,  when  it  is  seen  from  the 
point  of  view  of  the  enemy  or  of  the  prospective  victim,  against 
the  natural  background,  that  he  has  made  it  probable  that  nearly 
every  kind  of  natural  coloration  serves  for  concealment.  Patterns 
that  we  think  conspicuous,  and  brilliant  colours  that  we  have  tried 
to  explain  as  warning  or  advertising,  or  for  purposes  of  recognition, 
or  as  nuptial  plumage,  may  really  be  for  protective  or  aggressive 
concealment. 

There  is  no  arrangement  of  shading  so  common  in  the  animal 
kingdom  as  for  the  upper  surface  to  be  darker  than  the  lower  surface. 
Even  in  domestic  animals  we  are  accustomed  to  see  the  under  parts 
light  or  white  in  comparison  with  the  back,  although  among  these 
the  external  appearance  has  been  greatly  changed,  partly  by  the 
conscious  selection  of  man  and  partly  because  as  these  animals 
enjoy  human  protection  it  is  not  so  necessary  for  them  to  be 
concealed  from  their  natural  enemies  or  their  natural  prey.  But 
in  wild  nature  the  dark  shading  of  the  upper  surface  and  the 
lightening  of  the  lower  surface  seem  to  be  almost  the  rule.  The 
contrast  is  visible  even  in  the  tawny  lion  and  the  striped  tiger ; 
jaguars,  leopards  and  most  of  the  smaller  cats,  however  they  may 
be  spotted  or  striped,  show  it.  It  is  conspicuous  in  zebras,  wild 
asses,  deer,  sheep  and  goats  and  antelopes,  in  hares  and  rabbits, 
in  kangaroos,  in  whales  and  porpoises,  in  an  enormous  number  of 


76  CHILDHOOD  OF  ANIMALS 

birds,  in  snakes  and  lizards,  in  frogs  and  toads,  in  very  many  fish, 
whilst  most  of  the  creeping  insects  and  their  larvae  exhibit  it. 
There  is  no  obvious  difference  in  the  structure  of  the  body  to  account 
for  it ;  the  skin,  fur,  feathers  or  scales  are  formed  in  the  same  way 
from  similar  materials  all  over  the  body,  and  the  difference  cannot 
be  explained  as  the  visible  expression  of  anatomical  facts.  Nor 
can  it  be  explained  as  being  due  to  the  direct  action  of  sunlight, 
for  the  most  probable  effect  of  intenser  sunlight  on  tissues  is  to 
bleach  rather  than  to  stain,  and  if  there  be  a  difference  according 
to  habitat,  the  contrast  is  greater  in  many  of  the  swarthy  inhabi- 
tants of  forests  than  in  natives  of  the  open  plains. 

Although  we  do  not  know  the  physical  cause  of  this  common 
pattern,  Mr.  Thayer  has  shown  its  advantage  to  the  many  animals 
which  possess  it.  Professor  E.  B.  Poult  on,  of  the  University  of 
Oxford,  had  already  shown  how  in  some  caterpillars  the  distribution 
of  light  and  dark  shades  destroyed  the  rounded  appearance,  and 
made  the  plump  bodies  appear  flat  and  not  sharply  marked  off 
from  the  food-plant  on  which  they  were  resting,  but  Mr.  Thayer 
worked  out  the  idea  independently  and  showed  how  it  applied  on 
a  much  larger  scale.  If  a  white  billiard-ball  be  placed  on  a  table 
where  it  is  lighted  from  above,  or  carried  into  the  open  air  and 
similarly  exposed  to  the  sky,  it  will  be  seen  that  it  looks  round  and 
solid  chiefly  because  it  is  brilliantly  white  above  where  it  is  fully 
lighted,  and  almost  black  near  the  surface  on  which  it  is  resting, 
because  there  it  is  in  the  shade,  whilst  between  the  two  poles  the 
light  and  shade  gradually  pass  into  each  other.  Now  the  natural 
disposition  of  light  and  dark  colour  on  an  animal  is  so  arranged  as 
to  counteract  this  result  of  natural  illumination,  for  the  dark  shades 
are  found  on  the  upper  parts  where  the  illumination  is  greatest, 
and  the  light  shades  on  the  under  surface  where  the  illumination  is 
least.  The  natural  pattern,  in  fact,  is  a  counter -shading  of  the 
natural  illumination.  It  is  not  easy  to  get  any  pigment  to  adhere 
to  the  surface  of  a  billiard-ball,  but  if  two  rubber  balls  be  taken 
and  one  painted  white  all  over,  the  other  painted  white  on  one  end, 
black  on  the  other,  and  gradually  shaded  off  to  the  equator,  and 
then  the  two  balls  be  placed  alongside  where  they  are  illuminated 
from  above,  the  effect  will  be  seen  at  once.  The  white  ball  will 
look  round  and  solid,  white  above  and  dark  below ;  the  other  ball,  if 
it  be  placed  with  the  dark  pole  uppermost,  will  look  flat,  and  almost 
of  an  even  grey  tint  all  over. 

In  this  way  the  plump  solidity  of  the  natural  contours  of  an 


COLOUR  AND  PATTERN  IN  ANIMALS         77 

animal  fades  into  a  ghostly  elusiveness  against  its  natural  back- 
ground, especially  when  the  light  is  rather  diffused,  as  on  a  cloudy 
day,  or  where  a  creature  is  lurking  in  a  shadowy  corner  for  its  prey, 
or  tips  and  fades  kito  a  covert  when  it  is  being  pursued.  A  model 
(invented  by  Mr.  Thayer  and  often  exhibited  in  museums  shows  the 
real  invisibility  conferred  by  counter-shading.  Two  bird-shaped 
bodies  are  fixed  on  a  rod  that  can  be  revolved,  and  are  placed  in 
a  case  with  a  glass  roof  lighted  from  above,  with  the  side  next  the 
spectator  open  and  the  background  and  two  other  sides  painted 
with  neutral  grey.  The  body  of  one  bird  is  painted  all  over  as  nearly 
as  possible  the  same  shade  as  the  background ;  the  body  of  the 
other  is  darkened  above  and  made  lighter  than  the  background 
below.  At  a  little  distance,  the  self -tinted  model  stands  out  clearly 
from  the  background  as  the  solid  body  of  a  bird,  white  above  where 
it  is  illuminated,  dark  below  where  it  is  in  shadow ;  but  the  other 
model  is  almost  invisible,  for  the  counter-shading  neutralises  the 
effect  of  the  illumination.  If  the  rod  on  which  the  models  are 
fixed  be  rotated,  the  neutrally  tinted  body  remains  visible,  whilst 
the  counter-shaded  model,  as  its  shading  is  now  disposed  so  as  to 
agree  with  the  natural  lighting,  becomes  visible  at  once,  being  even 
more  conspicuous  than  the  other. 

So  also  if  a  white  rabbit  or  hare,  or  a  ptarmigan  in  its  white 
winter  plumage,  be  placed  in  a  similarly  constructed  case  with  a 
white  background,  we  shall  see  that  the  resemblance  in  colour  to 
the  background  does  not  protect  it.  On  the  other  hand,  if  it  be 
seen  in  bright  sunlight  on  a  glistening  surface  of  snow,  the  light 
reflected  up  from  the  snow  on  the  under  surface  of  its  body  to  a 
certain  extent  counteracts  the  natural  effect  of  light  and  shadow 
and  brings  about  a  fair  degree  of  invisibility.  The  polar  bear 
stalking  seals  at  the  edge  of  the  ice  probably  enjoys  a  similar 
softening  of  outline  from  reflected  light.  Desert  animals  may  also 
gain  something  from  the  light  reflected  upwards  from  the  sand,  and 
in  their  cases  the  contrast  between  the  upper  and  under  surfaces 
is  slight.  So  also  it  is  slight  from  another  reason  in  animals  that 
haunt  the  interior  of  shady  forests  ;  such  light  as  filters  through 
the  trees  is  diffused  and  obscure,  and  the  upper  surface  is  only  slightly 
darker  than  the  under  surface.  The  contrast  is  greatest  in  those 
animals  that  live  on  dark  ground  under  the  open  sky,  as  in  many 
of  the  rodents,  kangaroos  and  deer  that  live  on  open  plains. 

Counter-shading  is  a  character  tnat  may  be  found  in  various 
degrees  of  strength  combined  with  many  different  kinds  of  colora- 


78  CHILDHOOD  OF  ANIMALS 

tion  and  pattern,  the  utility  of  which  may  be  set  down  generally  as 
ways  of  matching  the  environment.  In  most  of  the  desert  animals 
the  various  shades  of  sandy  brown  known  as  "  khaki  "  and  used 
by  modern  armies  for  the  purpose  of  concealment  are  the  prevailing 
tints.  In  insects  that  live  on  green  foliage,  the  ground  colour  is 
frequently  a  shade  of  green.  In  ground-haunting  birds  like  snipe 
and  woodcock,  which  live  among  fallen  leaves  and  sticks  or  in 
weeds  and  grasses,  the  surface  is  blotched,  striped  and  mottled  in 
irregular  lines  and  patches,  which  resemble  the  usual  background, 
and  which,  with  the  addition  of  counter-shading,  make  an  almost 
perfect  concealment.  Especially  in  the  plumage  worn  during  the 
nesting  season  by  the  females,  the  surface  may  present  a  very 
elaborate  picture  of  the  leaves,  sticks  and  stones,  mossy  trunks, 
heather  and  so  forth  among  which  the  females  have  to  brood  on 
their  nests,  and  if  possible  remain  unnoticed  by  their  carnivorous 
foes,  so  that  they  may  preserve  their  own  lives  and  those  of  their 
helpless  young.  The  spotted  coats  of  leopards  and  jaguars,  and  of 
many  deer,  similarly  match  the  natural  background  of  light  shining 
through  the  interstices  of  foliage  ;  whilst  the  stripes  of  the  tiger 
and  of  many  of  the  antelopes  suggest  the  effects  of  light  and 
shade  thrown  by  tall  reeds  and  thick  grass. 

The  various  forms  of  matching  the  background  with  which  I 
have  been  dealing  are  most  successful  when  the  wearers  of  these 
liveries  are  at  rest,  and  their  utility  is  plainest  in  the  case  of  animals 
which  have  the  habit  of  squatting  on  the  ground,  whether  to  await 
their  prey  or  to  avoid  their  enemies.  Familiar  examples  are  the 
brooding  female  bird,  the  hare  squatting  in  its  form  on  the  open 
ground,  or  the  tiger  crouching  to  spring.  Another  and  more 
interesting  kind  of  protective  coloration  is  most  useful  to  males 
displaying  themselves  before  the  females  and  with  their  attention 
so  engrossed  that  they  are  not  on  the  watch  for  their  enemies,  or  to 
creatures  in  active  motion  in  pursuit  of  prey  or  in  search  of  food. 
Such  moving  creatures  come  under  different  effects  of  light  and 
shadow,  are  now  lighted  up  by  the  sun,  now  suddenly  brought 
against  a  light  background  or  a  dark  background,  and  are  under 
conditions  where  any  elaborate  matching  of  details  would  be  useless. 
Some  of  the  boldest  patterns  and  brightest  colours,  combinations 
that  seem  amazingly  conspicuous  in  a  cabinet  or  a  museum,  really 
serve  for  concealment  under  the  natural  conditions.  They  break 
up  the  natural  outline  of  the  animal,  which  would  be  otherwise 
conspicuous  by  the  uniformity  of  its  shape  against  the  irregularity 


COLOUR  AND  PATTERN  IN  ANIMALS         79 

of  its  surroundings.  The  great  white  patches  on  the  hindquarters 
of  many  deer  and  antelopes,  which  are  sometimes  expanded  when 
the  creatures  are  excited,  break  up  their  outline  when  seen  from 
behind.  The  black-and-white  markings  on  the  head  and  face 
and  the  curious  reversed  coloration  of  small  carnivores  like 
badgers  and  skunks  and  rat  els  make  them  more  conspicuous  to  us, 
but  when  seen  against  the  sky-line  at  dusk  by  the  small  prey  which 


FIG.  22. 


Oyster-catcher,  showing  counter-shading  and 
ruptive  pattern. 


they  hunt,  serve  to  make  them  invisible.  The  vivid  black-and- 
white  patches  of  many  shore  birds  (Fig.  22),  the  curious  appendages, 
the  secant  lines  across  the  body,  the  odd  markings  of  the 
head  so  common  in  birds,  serve  a  similar  purpose.  The  strangest 
and  most  violent  patches  of  colour,  the  bright  plumes,  and  the 
shifting  iridescences,  all  may  help  to  dazzle  the  eye  of  victim  or 
enemy.  We  must  always  remember  that  the  brightest  colour- 
schemes  of  an  artist's  canvas  look  pale  and  bleached  when  held 
against  the  brilliant  illumination  and  intense  coloration  of  actual 
outdoor  nature,  and  colours  and  markings  of  the  oddest  kinds  and 
most  irregular  shapes  may  be  the  best  disguises. 

As  I  have  already  said,  it  is  necessary  to  be  careful  to  distinguish 
between  the  possible  usefulness  of  coloration  and  the  causes  which 


80  CHILDHOOD  OF  ANIMALS 

have  brought  it  into  existence.  But  I  think  it  is  plain  that  as  we 
pass  from  the  patterns  that  are  the  fairly  obvious  result  of  growth- 
forces,  such  as  the  simple  geometrical  markings  which  are  visibly 
structural,  through  the  more  irregular  stripes  and  blotches  which 
may  be  set  down  to  irregular  growth,  to  counter -shadings  and 
elaborate  background-matching,  and  still  more  to  odd  and  brilliant 
disguises  of  the  true  contours  of  the  body,  we  come  into  regions 
where  we  may  more  and  more  expect  that  the  results  have  been 
shaped  and  controlled  by  a  process  of  natural  selection  and  serve 
some  purpose  of  direct  utility  to  their  possessors. 


CHAPTER  VI 
COLOURS  AND  PATTERNS  OF  YOUNG  MAMMALS 

THE  difference  in  coloration  between  young  mammals  and  their 
parents  often  depends  simply  on  immaturity.  The  skin  may  be 
smooth  and  soft,  the  scanty  hair  silky  in  texture,  and  the  general 
coloration  pale,  merely  because  the  young  animals  are  not  yet 
fully  developed,  because  their  structure  is  incomplete  and  the 
physiological  processes  which  produce  pigment  are  feeble  and  in- 
effective. The  little  creatures,  in  fact,  may  remain  partly  embryonic 
after  they  are  born,  and  differences  due  to  this  belated  development 
are  especially  plain  in  those  species  where  the  young  are  feeble  and 
most  dependent  on  their  parents.  The  first  liveries  acquired  by 
such  animals,  as  well  as  the  liveries  of  those  that  come  into  the 
world  active  and  furry,  often  differ  in  a  remarkable  way  from  the  full 
dress  of  the  adults.  If  the  adults  are  spotted,  the  young  are  always 
spotted  ;  if  the  adults  are  striped,  the  young  are  either  striped  or 
spotted  ;  even  if  the  adults  are  self-coloured,  or  have  acquired  one 
of  the  striking  patterns  of  the  higher  grades  that  not  only  do  not 
conform  with  the  architectural  lines  of  the  body  but  serve  to 
disguise  or  interrupt  these,  then  the  young  may  still  be  striped  or 
spotted. 

I  do  not  think  that  there  is  any  doubt  as  to  spots  and  stripes  being 
simple  growth  patterns,  outcrops  of  actual  structure,  and  not 
devices  that  have  been  invented,  so  to  speak,  by  nature  for  special 
purposes,  although  as  they  were  present  they  have  often  been  turned 
to  account.  A  good  many  years  ago,  Dr.  Bonavia,  an  ingenious 
surgeon-naturalist,  published  a  number  of  essays  on  the  markings 
of  mammals,  and  compared  such  patterns  as  the  dappling  of  horses, 
the  rosettes  of  the  jaguar,  the  spots  of  leopards  and  of  other  cats, 
with  the  armour-like  scales  of  armadillos  and  their  gigantic  extinct 
allies.  Certainly  many  of  the  extinct  mammals  were  armoured, 
and  if  we  go  back  still  further  to  the  reptilian  ancestors  of  mammals, 
we  come  to  a  set  of  creatures  in  which  a  coating  of  heavy,  sculptured 
scales  was  the  rule  and  not  the  exception.  It  would  be  pressing  the 

8* 


82  CHILDHOOD  OF  ANIMALS 

comparison  too  closely  to  insist  that  the  markings  of  modern 
mammals  were  the  actual  relics  of  lost  scales,  but  the  presence  of 
scales  and  of  spots  and  reticulations  and  stripes  (the  latter  being 
lengthened  spots  or  rows  of  spots  that  have  fused)  maybe  similar 
expressions  of  the  nature  of  the  external  covering  of  the  body.  The 
skin  is  not  a  continuous  sheet,  uniformly  stretched  over  the  body, 
but  is  a  composite  structure  growing  from  many  centres,  supplied 
by  different  nerves  and  blood-vessels,  and  may  well  reveal  this 
composite  character  by  a  tessellated  appearance,  retaining  this 
where  it  is  useful,  or  harmless,  as  in  the  well-guarded  young,  or  in 
the  least  conspicuous  parts  of  the  body  of  adults,  or  have  it  obliterated 
where  it  is  harmful. 

The  possibility  of  changing  the  pattern  and  colour  of  the  exterior 
of  the  body  comes  about  in  mammals  and  birds  because  these  for 
other  reasons  are  able  to  moult.  Animals  have  to  contend  not 
only  with  the  larger  kinds  of  foes  which  are  able  to  pounce  on  them, 
kill  them  and  devour  them  bodily,  but  with  a  multitude  of  minute 
enemies  which  harbour  on  the  outside  of  their  bodies  and  injure  their 
health  in  many  ways.  The  spores  of  bacteria  and  moulds  are  rained 
on  them  from  the  dust  of  the  air,  are  rubbed  on  them  by  contact,  or 
are  floated  on  them  in  water.  Fleas  and  bugs,  lice  and  ticks,  a 
prolific  swarm  of  hungry  vermin,  provided  with  biting  and  sucking 
organs,  grasping  hooks,  claws  with  adhesive  pads,  and  devices 
innumerable  for  maintaining  their  position  if  once  they  reach  the 
body,  assail  them.  These  parasites  may  do  much  or  little  direct 
harm  ;  sometimes  they  feed  only  on  the  waste  secretions  of  the  body 
and  do  little  more  than  cause  a  tickling  irritation  ;  sometimes  they 
burrow  deeply,  or  scratch  and  gnaw  until  they  produce  serious 
wounds,  or  weaken  their  host  from  direct  loss  of  blood.  Still 
more  often  those  that  are  blood-suckers  do  damage,  not  only  directly, 
but  by  introducing  the  seeds  of  diseases  that  may  be  fatal, 
carrying  them  from  infected  to  healthy  animals.  Many  of  the 
soft-skinned  lower  animals,  such  as  newts  and  frogs,  and  still  more 
worms  and  slugs,  whose  bodies  would  otherwise  be  a  ready  prey,  are 
protected  from  the  attacks  of  external  parasites  by  their  power  of 
producing  slimy  secretions  which  float  off  the  lintruders  before  these 
have  time  to  establish  themselves.  Other  animals  keep  their  skins 
clean  by  a  process  acting  like  the  scaling  paints  with  which  the  sub- 
merged parts  of  warships  are  covered,  to  prevent  their  bottomsrgetting 
fouled  with  barnacles.  The  outer  horny  layer  of  the  skin  is  constantly 
shed  off,  carrying  with  it  many  of  the  parasites  and  leaving  the 


COLOURS  AND  PATTERNS  OF  MAMMALS      83 

surface  clean.  Sometimes  this  process  is  slow  and  continuous; 
as  in  ourselves,  sometimes  it  takes  place  at  regular  intervals,  in 
large  sheets  which  may  extend  to  the  whole  body,  as  when  a  serpent 
sloughs,  casting  off  the  complete  outer  layer  of  the  skin,  even  to  the 
transparent  membrane  of  the  eye. 

The  warm  coats  of  fur  or  feathers  which  protect  the  bodies  of 
most  mammals  and  birds  are  formed  chiefly  of  the  outer  horny 
layers  of  the  skin,  and,  within  certain  limits,  can  be  cast  off  and 
renewed.  This  process  of  moulting  is  useful  in  many  ways.  It 
gives  the  opportunity  of  replacing  coats  that  have  become  worn 
and  faded,  by  coats  that  are  bright  and  clean.  It  gives  the  oppor- 
tunity for  a  change  of  clothing  from  the  warm  covering  necessary 
in  winter  to  the  lighter  covering  which  is  more  healthy  in  warm 
weather,  and  perhaps  most  important  of  all,  it  makes  possible 
periodical  changes  in  colour  and  pattern.  Just  as  when  the  outer 
layers  of  the  skin  are  shed  off  they  may  be  replaced  by  differently 
coloured  layers,  so  the  old  hairs  or  feathers,  when  they  fall  off,  may 
be  replaced  by  hairs  and  feathers  with  different  colours  and  patterns. 
It  is  the  process  of  moulting  far  more  than  any  actual  change  in 
skin,  fur  or  feathers  that  underlies  the  differences  between  young 
and  old  animals,  or  between  mature  animals  at  different  seasons  of 
the  year. 

Lemurs,  monkeys  and  human  beings  form  the  most  highly  modified 
group  of  mammals,  the  group  that  is  furthest  removed  from  the 
reptilian  ancestors,  and  I  do  not  know  of  any  in  which  either  the  young 
or  the  adults  are  spotted  or  striped,  except  that  the  tails  are  some- 
times ringed.  The  skin  is  usually  dark,  but  there  may  be  brightly 
coloured  patches  on  the  face  and  other  areas  not  covered  with  hair, 
and  these,  whatever  their  use  may  be,  fall  into  the  higher  grades  of 
coloration  and  do  not  conform  with  the  structural  lines  of  the  body. 
The  hair  also  is  either  uniform,  or  decorated  with  crests,  ridges  or 
tufts  which,  like  the  patches  on  the  naked  skin,  seem  to  be  late 
additions  to  the  coloration  of  the  body,  and  differ  much  in  closely 
allied  species.  Monkeys,  like  human  beings,  moreover,  have  lost 
the  habit  of  moulting  regularly,  and  are  continually  shedding  off 
and  renewing  their  hairs.  The  change  is  modified  by  exposure  to 
cold,  and  the  coats  of  those  that  have  access  to  the  open  air  all  the 
year  round  become  longer  and  thicker  than  those  of  animals  housed 
in  heated  apartments.  And  so  there  are  no  startling  differences 
between  the  young  and  the  adults.  Like  human  beings,  young 
monkeys  are  born  with  a  very  scanty  coat  of  silky  hair,  large  parts 


84  CHILDHOOD  OF  ANIMALS 

of  the  body  being  naked.  The  face,  hands  and  feet  are  usually 
black  in  monkeys,  but  just  as  the  hands  and  feet  of  negro  infants 
are  paler  in  colour,  so  these  regions  in  very  young  monkeys  are  white 
or  pink  (see  Plate  IX,  p.  1 65) .  A  complete  coat  of  fur  appears  in  a  few 
months,  and  if  there  be  no  difference  between  the  sexes,  it  is  like 
that  of  the  adult  from  the  first,  but  paler.  The  face  and  hands 
acquire  the  pigmentation  more  slowly,  and  if  there  are  brightly 
coloured  patches  of  naked  skin,  these  are  the  last  to  appear  and  do 
not  acquire  their  full  richness  until  the  animal  is  almost  adult.  So 
also  the  beards,  crests  and  special  tufts,  often  strongly  marked  in  the 
males,  appear  towards  maturity.  The  three  plates  (I,  Frontispiece  ; 
IX,  p.  165  ;  and  X,  p.  166)  showing  young  anthropoid  apes,  and 
human  children,  the  mother  and  young  of  a  langur  monkey  and  of 
a  lemur  all  show  the  similar  differences  between  young  and  adults. 

The  Cats,  great  and  small,  show  abundant  traces  of  a  primitive 
spotted  pattern.  The  spots  are  most  frequent  in  the  young.  In 
some  they  are  retained  throughout  life  over  the  whole  body  in  both 
males  and  females  ;  in  others  traces  of  them  remain  on  the  under 
parts,  or  on  the  sides,  especially  in  the  females  ;  in  others,  again,  they 
are  found  in  the  winter  fur  but  disappear  in  the  summer  fur.  In 
some  they  have  elongated  or  fused  to  form  stripes,  or  are  twisted 
into  spiral  markings.  In  others  they  are  obliterated,  being  washed 
over,  so  to  speak,  with  an  even  tint,  and  this  tint  may  be  still 
further  elaborated  by  the  appearance  of  special  markings,  coloured 
manes  and  so  forth.  The  whole  group  shows  extremely  well  the 
replacement  of  the  primitive  growth  pattern  by  patterns  of  higher 
grade.  The  changes  in  coloration  are  produced  either  by  a  gradual 
loss  and  replacement  of  the  individual  hairs — and  this  usually  takes 
place  in  the  natives  of  tropical  countries — or  by  a  regular  moult  at 
the  beginning  of  the  warm  season  and  a  slighter  moult  with  a  rapid 
growth  of  thick  fur  at  the  beginning  of  the  cold  season.  The 
winter  coat  is  often  lighter  in  colour  because  of  the  growth  of  a  very 
thick  under- fur  ;  sometimes,  as  in  the  Northern  lynx,  it  is  more 
spotted,  but  usually  it  is  paler  and  less  brightly  marked  with 
shades  of  black  and  orange  than  is  the  spring  breeding  pelage. 

The  young  are  always  born  with  a  thick  and  soft  coat  of  fur. 
In  the  tiger  and  the  striped  cats  and  in  all  the  spotted  cats,  the 
coloration  of  this  differs  from  that  of  the  adult  only  in  being  rather 
paler,  whilst  in  those  cats  which  are  brown  in  the  adult  condition  the 
^oung  are  profusely  spotted.  Young  lions  are  thickly  set  with  spots, 
especially  on  the  sides  and  under  parts,  whilst  the  tail  shows  signs 


COLOURS  AND  PATTERNS  OF  MAMMALS      85 

of  dark  rings  (Plate  III,  p.  62).  Although  pumas  are  nearly  uni- 
formly coloured,  tawny-brown  in  winter  and  redder  brown  in 
spring,  their  cubs  are  vividly  marked  with  black,  stripes  and  spots 
on  the  face,  a  broad  band  on  each  side  of  the  face,  spots  on  the 
legs  and  under- parts,  and  rings  on  the  tail.  Caracals,  until  they 
shed  their  puppy  coat  when  they  are  about  six  months  old,  are  very 
brightly  spotted  on  the  under  surface,  whilst  lynxes,  which  are 
greyish- brown  in  their  adult  summer  coats,  are  profusely  spotted 
with  black  when  they  are  young. 

The  young  of  these  cats  are  so  carefully  hidden,  and  so  zealously 
guarded  by  the  mother — who  is  more  ferocious  in  defence  of  her 
cubs  than  the  females  of  other  species — that  they  have  little  need 
of  the  protection  that  concealment  might  give.  I  do  not  doubt  but 
that  a  spotted  coat  serves  as  a  protection,  partly  by  breaking  up  the 
outline,  and  still  more  in  the  case  of  those  animals  that  live  in  the 
forest  and  crouch  for  their  prey  at  the  edges  of  open  glades,  or 
lie  along  the  branches  of  trees  where  their  marks  would  blend  with 
the  dappled  disks  of  light  and  patches  of  shadow  formed  as  the 
sunlight  filters  through  the  foliage.  It  is  more  than  probable 
that  the  spotting  of  adult  jaguars  and  leopards,  servals  and  cheetahs, 
and  the  various  spots,  stripes  and  blotches  of  the  smaller  cats  are 
the  patterns  of  the  young,  retained  and  made  more  vivid  by  natural 
selection.  It  is  usual  to  see  a  relation  between  the  vertical  shadows 
thrown  by  reeds  and  tall  grasses  and  the  striping  of  the  tiger,  and  it 
is  a  fair  supposition  that  the  coat  of  that  splendid  cat  is  a  still  further 
modification  of  a  primitively  spotted  livery.  The  self  colour  of 
lions,  pumas,  caracals  and  lynxes  has  unquestionably  come  about 
by  the  obliteration  of  the  spots  found  in  the  young,  and  in  adult 
life  traces  of  spots  remain  in  varying  degrees,  but  most  strongly  on 
the  under  surface  and  on  the  legs  where  they  are  least  conspicuous. 
It  seems  certain  that  the  spotted  skin  of  young  cats,  like  that  of 
many  other  animals  to  which  we  shall  come  later,  is  a  natural  growth 
pattern  which  is  retained  in  adult  life  where  it  is  useful,  or  accentu- 
ated by  transformation  into  stripes,  or  obliterated  to  a  self  colour. 

The  small  carnivores,  such  as  civets,  genets  and  linsangs,  bintu- 
rongs,  ichneumons  and  mungooses,  show  a  similar  general  set  of 
patterns.  In  almost  any  group,  some  are  spotted,  others  are 
striped,  whilst  in  a  few  of  the  adults  the  coloration  is  nearly  uniform 
except  for  the  usual  counter-shading,  and  it  is  not  difficult  to  see  a 
general  relationship  between  the  kind  of  coloration  and  the  nature 
of  the  ground  in  which  the  animals  are  habitually  found.  In  all 


86  CHILDHOOD  OF  ANIMALS 

cases  where  the  adults  are  spotted  or  striped,  the  young  are  spotted 
or  striped  ;  I  do  not  know  of  any  case  where  a  self-coloured  young 
acquires  spots  in  the  adult  condition.  On  the  other  hand,  some 
at  least  of  those  which  are  unspotted  in  the  adult  condition,  such 
as  the  binturong,  are  spotted  and  blotched  when  they  are  young. 
As  the  kittens  of  all  these  animals  are  born  in  holes,  and  are  sedu- 
lously guarded  by  the  mothers,  the  existence  of  spotted  young  cannot 
easily  be  explained  as  a  special  adaptation  for  protection,  but  is  a 
survival  from  some  remote  ancestral  condition. 

In  hyaenas,  wolves,  dogs  and  foxes,  there  is  seldom  much  differ- 
ence in  pattern  between  the  young  and  the  adults,  although  the  fur 
is  shorter  and  usually  thicker,  and  spots  are  common  on  the  under 
parts.  Some  of  the  jackals  have  distinctive  liveries,  and  in  these  the 
cubs  are  more  simply  coloured.  The  black-backed  jackal,  for 
instance,  has  the  sides  reddish,  the  legs  and  the  upper  part  of  the 
tail  yellowish-red,  whilst  the  back  and  the  end  of  the  tail  are  black ; 
but  the  cubs  are  nearly  uniformly  coloured,  a  dusky  brown  above 
and  yellowish- brown  below.  The  canine  animals  vary  a  good  deal  in 
their  mode  of  moulting,  but  the  northern  forms  have  a  fairly  definite 
autumn  and  spring  moult.  Arctic  loxes,  for  instance,  which  are 
white  in  winter,  shed  the  greater  part  of  the  summer  coat  in  a  few 
weeks,  replacing  it  gradually  by  the  thick  white  winter  coat ;  whilst 
in  early  summer  or  spring  of  the  following  year  they  again  shed  the 
winter  coat  and  replace  it  by  the  thinner,  dark  summer  pelage.  I 
do  not  know  how  soon  the  cubs  of  Arctic  foxes  become  white  ;  I 
should  guess  from  analogy  that  it  is  not  until  the  second  winter, 
as  the  puppy  coat  of  most  canine  animals  persists  as  the  first 
winter  coat,  and  the  moult  takes  place  next  spring,  the  puppy  then 
acquiring  the  usual  characters  of  the  adult.  Nepal  mastiffs  in  the 
London  Zoological  Gardens  moulted  their  under-fur  early  in  spring. 

Young  bears  are  extremely  like  the  adults,  and  the  puppy  coat 
appears  to  be  retained  as  the  first  winter  coat.  The  tropical  bears, 
such  as  the  Himalayan,  sloth  and  sun  bears,  change  the  hairs  singly, 
and  have  no  thick  under- fur.  The  polar  bear  sheds  the  thick  under-fur 
and  a  considerable  portion  of  the  whole  coat  in  the  water  rather 
early  in  spring,  at  least  in  the  case  of  bears  in  captivity  ;  in  autumn 
much  of  the  coat  is  shed  singly  hair  by  hair,  but  the  chief  change  is 
the  growth  of  a  thick  under- fur.  The  brown  bears  and  grizzlies 
moult  off  the  thick  winter  fur  in  masses  early  in  spring.  With 
bears,  like  most  of  the  wolves,  dogs,  foxes  and  jackals,  there  is  no 
striking  difference  between  the  patterns  of  the  young  and  the  adults. 


COLOURS  AND  PATTERNS  OF  MAMMALS      87 

The  many  families  of  small  carnivores,  such  as  raccoons,  pandas, 
coatis,  martens,  polecats,  weasels,  gluttons  and  skunks,  ratels, 
badgers  and  otters,  have  generally  brilliantly  marked  fur,  with  ringed 
tails,  striped  bodies,  or  conspicuous  marks  on  the  head  or  body  ; 
nearly  all  of  them  have  an  autumn  and  a  spring  moult,  and  there  are 
many  cases  where  the  pelage  of  summer  and  winter  is  notably  differ- 
ent, in  colour  as  well  as  in  quality.  The  young  are  born  in  holes  or 
nests,  usually  in  an  imperfect  condition,  nearly  always  blind,  and 
sometimes  naked,  as  in  the  polecats  and  mink.  Even  if  they  are 
born  with  fur,  the  first  coat  is  fine  and  silky,  very  often  white  in 
colour,  and  this  towards  the  end  of  the  autumn  is  gradually  replaced 
by  a  rough  puppy  coat  which  persists  until  the  spring  moult.  It  is 
possible  that  the  light  colour  of  the  first  coat  may  make  the  animals 
more  visible  to  the  mother  in  the  dark  holes  or  nests  where  they  are 
born.  They  are  born  in  an  immature  condition  partly  because  the 
mothers  have  to  catch  their  prey  by  agility  and  would  have  difficulty 
in  obtaining  a  living  when  heavy  with  young. 

The  seals  are  probably  terrestrial  carnivores  which  have  taken  to 
living  in  the  water,  although  they  come  ashore  to  breed.  The 
young  are  born  covered  with  hair  and  in  a  well-developed  condition. 
The  young  of  the  eared  seals,  which  include  the  fur  seals,  sea-lions 
and  sea-bears,  are  able  to  swim  in  an  hour  or  two  after  their  birth,  and 
the  first  coat  is  thick  but  silky  and  in  almost  every  case  very  much 
darker  than  the  pelage  of  the  adults.  The  young  of  the  true  seals, 
which  have  no  external  ears  and  in  which  the  hind-legs  are  turned 
backwards  and  dragged  after  the  body  on  land,  instead  of  being  used 
for  progression,  show  a  curious  reluctance  to  take  to  the  water,  and 
may  spend  weeks  on  shore.  They  are  born  with  a  white  and  silky 
coat  which  is  shed  very  quickly,  and  replaced  by  a  longer  and  more 
woolly  puppy  coat.  In  the  grey  seal  familiar  on  the  wilder  parts 
of  the  coast  of  Great  Britain,  the  young  are  at  first  pure  white,  with 
silky  hair,  but  in  a  few  days  this  coat  becomes  yellower  and  woolly, 
partly  by  the  growth  of  new  hairs  ;  in  about  six  weeks  this  infantile 
coat  is  moulted  off  and  replaced  by  a  shorter  and  thicker  coat  of 
particolour,  yellow  mottled  with  grey  and  black.  In  about  seven 
months  there  is  a  second  moult  and  the  third  pelage  resembles  that 
of  the  adult,  but  this  may  not  be  fully  attained  until  after  another 
moult.  The  colours  of  the  adult  vary  much,  and  there  seems  to  be 
no  special  meaning  in  the  changes  at  the  successive  moults. 

The  young  of  all  the  ruminating  Ungulate  animals  are  born  in  an 
advanced  condition,  and  it  is  by  far  the  most  usual  case  for  the  pelage 


88  CHILDHOOD  OF  ANIMALS 

to  differ  little  from  that  of  the  adult,  except  in  the  absence  of  specially 
marked  manes  and  beards.  All  those  that  live  in  cold  countries 
assume  a  thick  winter  coat  which  they  shed  in  spring,  and  the  pattern 
of  this  coat  may  be  a  little  different,  whilst  its  hairs  are  longer, 
more  closely  set  and  rather  woolly.  The  young  animal  begins  to 
assume  the  appearance  of  the  adult  in  the  spring  after  its  first  winter, 
but  usually  moults  once,  a  few  weeks  after  it  is  born,  replacing  a 
sparse  puppy  coat  of  rather  long  and  silky  hair  by  a  thicker  coat. 

Amongst  cattle  there  is  little  difference  between  young  and  adults, 
but  the  coat  of  the  young  is  usually  lighter  and  redder,  and  where  the 
adult  has  a  strongly  contrasting  pattern  of  black  above  with  white 
under  parts  and  white  "  stockings,"  this  is  less  conspicuous  in  the 
young,  suggesting  that  the  adult  pelage  is  a  later  acquisition.  Thus  an 
adult  wild  gayal  bull  has  an  almost  black  back,  with  white  stockings  ; 
the  calf  is  brownish- red  with  only  the  inner  sides  of  the  legs  white, 
whilst  the  young  banteng  is  coloured  like  the  young  gayal,  except 
that  it  has  a  dark  stripe  along  the  back.  In  sheep,  goats  and 
chamois  the  patterns  of  the  young  and  the  adults  are  almost  identical, 
although  in  some  of  the  brightly  patterned  wild  sheep,  like  the 
mouflon,  the  young  show  almost  no  trace  of  the  diversified  coloration. 

The  great  family  of  antelopes  show  many  conspicuous  colour 
patterns,  and  differences  between  the  young  and  the  adult  are  frequent. 
The  hartebeestes,  bontebok  and  gnus  live  for  the  most  part  in  open 
plains,  and  except  for  counter-shading  are  usually  self-coloured  in 
some  yellow,  brown  or  re  dish  shade,  with  various  bands  or  blotches  of 
black  and  white,  such  as  round  the  upper  parts  of  the  legs,  on  the 
face  or  on  the  rump,  which  certainly  have  a  ruptive  effect — that  is 
to  say,  they  break  up  the  natural  outline  and  obscure  the  contours, 
when  seen  from  a  distance.  The  calves  are  much  more  uniformly 
tinted,  suggesting  that,  as  in  the  cattle,  the  conspicuous  patterns  of 
the  adult  are  later  acquisitions.  The  duikers,  a  family  of  antelopes 
with  very  small  horns,  which  haunt  long  grass  and  brushwood,  have 
a  coloration  ranging  from  pale  mouse-colour  to  bright  bay,  whilst 
many  of  them  have  broad  dorsal  bands  or  saddles  of  black  or  white  or 
yellow,  and  various  face  and  head  marks  which  have  a  secant, 
outline -interrupting  effect,  and  in  these  the  young  show  the  con- 
spicuous pattern  of  the  adult  in  a  very  faintly  marked  fashion,  if 
at  all.  There  is  one  striking  exception,  however.  The  banded  or 
zebra  duiker  of  Liberia  (Fig.  23)  has  the  tawny  back  marked  with 
bands  of  black  arranged  like  the  hoops  of  a  barrel,  and  this  pattern  is 
practically  alike  in  the  male,  female  and  young.  The  klipspringer, 


COLOURS  AND  PATTERNS  OF  MAMMALS      89 

oribis,  dik-diks  and  the  reed-bucks,  water-bucks  and  kobs  are  seldom 
brightly  patterned,  and  the  young  are  very  much  like  the  adults. 
In  the  very  large  family  of  gazelles  the  patterns  are  seldom  con- 
spicuous ;  the  general  coloration  is  a  shade  of  fawn,  lighter  below, 
frequently  much  darkened  on  the  back,  especially  in  old  males, 
whilst  face  markings,  rump  patches  and  lateral  stripes  are  frequent 
Where  the  young  differ  from  the  adult,  they  are  almost  invariably 
more  uniformly  coloured.  In  the  large  sable,  roan,  oryx  and  beisa 
antelopes,  brilliant  secant  and  ruptive  pattern  is  frequent,  the 


FIG.  23.     Young  and  Adult  Banded  Duiker  Antelope. 
(After  JENTINCK.) 

general  browns  and  tawny-reds  being  interrupted  with  vivid  patches 
and  streaks  of  black  and  white.  The  coloration  of  the  young  is 
much  simpler,  the  general  uniformity  being  little  interrupted.  The 
very  beautiful  tragelaphine  antelopes,  which  include  the  largest 
members  of  the  group,  show  an  interesting  condition.  The 
males  and  females  are  often  very  different  in  coloration,  the  males 
being  much  darker,  sometimes  almost  black,  whilst  the  females  are 
usually  reddish- brown.  Stripes  and  spots  of  different  kinds  are 
present  in  so  many  members  of  the  group  that  they  seem  to  be  an 
ancestral  property.  There  are  often  large,  rather  irregularly  placed 
white  spots  on  the  hindquarters,  and  there  may  be  lines  of  spots 
along  the  flanks,  or  these  maybe  joined  to  form  continuous  stripes. 
Finally,  there  may  be  spots  arranged  in  the  form  of  hoops  across  the 
back,  but  in  most  cases  these  rows  are  actually  joined  to  form  bands. 


9o  CHILDHOOD  OF  ANIMALS 

The  young  almost  invariably  resemble  the  females  in  general  tawny 
coloration,  and  have  the  stripes  and  spots  more  brightly  marked 
than  in  the  adults.  The  new-born  calves  of  the  South  African 
eland,  which  is  the  common  species  in  Zoological  Gardens,  are 
born  with  rather  a  shaggy  coat  the  longer  hairs  of  which  are  shed 
very  soon,  and  then  the  barrel-hoop  stripes  of  white  become  visible, 


/ 

/••"••"  •'•'-•  ..*--• 

zr   "*"     ^-—^-^"x  ***  "'  '•" 


FIG.  24. 


Young  and  Adult  Selous'  Sitatunga  Antelope. 
(Partly  after  SCLATER  and  THOMAS.) 


but  fade  out  as  the  animals  grow  up,  usually  remaining  rather 
brighter  in  the  females  and  being  nearly  obliterated  in  the  males. 
In  the  Derbian  eland  they  remain  more  visible  in  both  sexes,  and  the 
same  occurs  in  the  kudus.  The  young  Selous'  sitatunga  antelope 
(Fig.  24)  has  a  livery  of  reddish-brown  with  spots  on  the  flanks,  and 
rows  of  spots  just  fusing  into  barrel  hoops  across  the  back  ;  but  these 
have  faded  out  almost  completely  in  the  adult  female,  and  com- 
pletely in  the  adult  male,  which  is  dark  brown.  In  Speke's  sitatunga 
and  the  Congo  sitatunga,  the  contrast  between  adult  males  and 
females  is  not  so  great  ;  slight  traces  of  the  stripes  are  retained  in  the 
male,  rather  more  in  the  female,  whilst  the  young  is  as  richly  marked 


COLOURS  AND  PATTERNS  OF  MAMMALS      91 

as  the  young  Selous'  sitatunga.  The  splendid  bongo  and  angas 
antelopes  retain  the  spots  and  hoops  of  the  young  in  both  sexes, 
although  in  the  latter  the  adult  male  becomes  nearly  black.  The 
young  harnessed  antelope  has  spots  on  the  hindquarters,  stripes 
along  the  side,  and  barrel  hoops  across  the  back,  and  a  general 
reddish  hue  very  like  the  young  sitatunga ;  whilst  these  fade  but  still 
remain  visible  in  the  darker  adults.  The  male  nilgai  or  "  blue  bull " 
of  India  is  bluish- black,  whilst  the  female  and  the  young  are  tawny 
and  there  is  no  trace  of  spots  and  stripes  in  any  of  them. 

In  antelopes  generally  there  is  to  be  noticed  the  same  general 
tendency  that  occurs  amongst  the  carnivores.  When  the  young 
differ  in  pelage  from  the  adults,  they  resemble  the  females  more 
closely  than  the  males  ;  they  show  far  less  trace  of  special  ruptive 
and  secant  patterns,  of  those  patterns  which  follow  the  primitive 
contours  of  the  body  least,  and  show  frequent  traces  of  spots  and 
stripes,  and  similar  simple  growth  patterns. 

The  prongbuck  or  American  antelope,  which  lives  in  upland 
prairies  and  on  rocky  slopes  where  the  snow  lies  in  patches  until 
late  in  spring,  and  descends  again  in  early  autumn,  is  one  of  the 
most  striking  examples  of  ruptive  pattern.  The  back  is  rich  tan 
with  black  on  the  head,  and  great  disks  of  white  on  the  rump,  whilst 
the  face  and  sides  have  patches  and  areas  of  white  sharply  marked 
off  from  the  darker  regions.  The  females  have  similar  but  less 
brightly  marked  patterns,  whilst  the  young  are  almost  uniformly 
clad  in  pale  greyish- brown  with  only  the  faintest  trace  of  the  adult 
coloration.  Here  is  another  instance  of  one  of  the  highly  specialised 
patterns  which  cannot  be  easily  associated  with  the  natural  structure 
of  the  body,  appearing  only  with  adult  life. 

The  well-known  pattern  of  the  Giraffes  (see  Plate  II,  p.  n)  suggests 
in  a  vivid  way  the  origin  of  colour  pattern  from  the  tessellated  or 
particulate  character  of  the  skin.  It  consists  of  a  series  of  spots  or 
blotches  which  grow  darker  with  age,  placed  on  a  pale  background, 
and  in  some  species  leaving  only  a  narrow  reticulation  of  the  pale 
ground  between  the  spots.  The  young,  as  soon  as  they  are  born, 
show  the  spots  clearly  marked.  Many  hunters  have  borne  witness 
to  the  fashion  in  which  this  apparently  vivid  pattern  makes  the 
animal  almost  invisible  as  it  stands  under  the  trees  on  which  it 
feeds,  and  it  appears  as  if  the  pattern  were  a  simple  growth  form 
that  had  been  retained  because  it  was  either  positively  useful  or  at 
least  harmless. 

Deer  show  a  most  interesting  set  of  differences  in  the  relations 


92  CHILDHOOD  OF  ANIMALS 

between  the  young  and  adult  patterns.  The  young,  in  by  far  the 
greater  number  of  species,  are  spotted,  and  although  it  must  cer- 
tainly be  the  case  that  this  pattern  helps  to  conceal  a  fawn  lying 
quietly  in  the  shadow  of  trees,  the  presence  of  spots  is  so  common, 
whether  the  deer  inhabit  woodland  or  not,  that  it  seems  more 
natural  to  think  of  it  as  a  primitive  growth  character  such  as  is 
found  in  many  other  groups.  In  some  deer  the  spots  are  retained 
throughout  life.  The  beautiful  axis  deer  is  always  brilliantly 
spotted,  and  as  it  haunts  the  neighbourhood  of  trees  and  comes  out 
readily  in  the  daylight,  it  may  well  be  that  its  dappled  hide  is  a 
protection.  The  Formosan  deer  is  brightly  spotted  in  its  summer 
coat,  and  the  spots  persist,  although  they  are  less  plainly  marked; 
in  the  lighter  winter  coat.  The  fallow  deer  are  also  haunters  of 
woods  and  forests ;  in  the  most  familiar  form  they  are  brightly 
spotted,  like  the  fawns,  but  the  spots  disappear  with  age,  and 
local  varieties  are  known  without  spots,  whilst  it  has  been  recorded 
that  some  of  the  fawns  are  unspotted.  In  the  Japanese  deer  the 
fawns  are  spotted,  but  the  adults  in  winter  are  uniformly  clad  in 
dark  brown,  and  change  again  in  summer  to  a  lighter  spotted  coat. 
The  fawns  of  the  hog-deer  and  the  Barasingha  or  swamp-deer  are 
spotted,  and  there  are  rows  of  spots  in  the  brighter  summer  pelage  of 
the  adults,  which  are  lost  in  winter,  to  be  renewed  again.  In  a  very 
large  number  of  deer  belonging  to  different  groups  and  with  very 
different  haunts  and  habits,  the  spotted  coat  of  the  fawn  is  shed  in  a 
few  months,  and  although  there  may  be  regular  changes  from  summer 
to  winter  and  from  winter  to  summer  pelage  the  spots  never  again 
reappear.  This  happens  with  the  common  red  deer  (see  Plate  V)  and 
wapiti  and  their  allies  all  round  Europe,  Asia  and  North  America, 
with  Eld's  deer,  roe-deer,  the  Chinese  water-deer,  the  curious  little 
brocket  deer  of  America,  the  Virginian  deer,  the  mule-deer  and 
the  very  peculiar  musk-deer.  Finally,  there  are  a  few  deer  belonging 
to  different  groups  in  which  there  is  no  trace  of  spots  in  the  young 
or  the  adult.  Amongst  these  are  the  Sambur  deer,  except  the 
Philippine  Islands  form,  the  muntjacs,  reindeer,  elk  and  the  Ameri- 
can guemals  and  pampas  deer.  It  is  at  least  interesting  to  notice 
that  spots  tend  to  disappear  in  winter  coats  and  in  the  northern 
races  of  deer,  and  that  they  are  retained  in  deer  which  are  not 
nocturnal. 

The  pig-like  little  chevrotains  or  mouse-deer  come  very  close  to  the 
ruminants,  but  do  not  actually  ruminate,  and  in  many  ways  are 
intermediate  between  deer  and  pigs,  certainly  representing  a  very 


PLATE  V 

GROUP  OF  RED-DEER:   STAG,  TWO 
HINDS  AND  A  SPOTTED  FAWN 


•     V:::    : 

1  adult 

. 

nhabit  woodland  o; 
c  of  it  as  a  primit; 
other  groups.     In  some 
life.     The   beautiful   axis 

1  as  it  haunts  the  neighboui  s  out 

ai  the  daylight,  it  may  w< 
••~>n.     The  Formosan  de« 

.  and  the  spots  persist  ked, 

•he  lighter  winter  coat.  -s  Of 

••Is  and  forests;    in 

spotted,  bfce^    ;  |O^O 

local  varietlfe^u -A  q  {  .  n  rded 

that  some  of  i.  In  t' 

fawns  are  spotted,  but  -n  winter  are  u  d  in 

dark  brown,  an.--  ,  a  Hg!, 

The  fawns  of  the  h  r  are 

spotted,  and  there  are  rows  of  spots  in  t  ;>elage  of 

the  adults,  which  are  lost  in  winter,  to  be  rene\v  i.     In  a 

large  number  of  deer  belonging  to  different  groups  and  with  very 
different  haunts  and  habits,  the  spotted  coat  of  the  fawn  is  shed  in  a 
few  months,  and  although  there  may  be  regular  changes  from  summer 
to  winter  and  from  winter  to  summer  pelage  t  ..gain 

reappear.     This  happens  with  the  comir  and 

wapiti  and  their  allies  all  round  Europ 

with  Eld's  deer,  roe-deer,  the  Chint  ittle 

brocket  deer  of  America,  the  Vir- 
the  very  peculiar  musk-deer.  Final] 
to  different  groups  in  which  there  i 

or  the  adult.    Amongst   these  an'  the 

Philippine  Islands  form,  the  mur  :  the  Ameri- 

^uemals  and  pampas  deer.     It  otice 

spots  tend  to  disappear  ii  hern 

of  deer,  and  that  they  are  i  not 

not 

Tlie  pig-like  little  chevrotains  or  mouse-deei  come  e  to  the 

ruminants,  but  do  not  actually  nr 

mediate  between  deer  and  -  a  very 


COLOURS  AND  PATTERNS  OF  MAMMALS      93 

primitive  type  of  animal  that  has  survived.  In  the  Indian 
chevrotain  and  the  African  water  chevrotain,  the  bodies  of  the 
young  and  adults  are  alike,  reddish- brown,  and  much  spotted  with 
v/hite,  the  spots  being  often  joined  to  form  bands.  In  the  adults 
of  two  other  species  found  in  the  Malay  archipelago  the  coloration 
is  more  uniform,  darker  above  and  lighter  below  ;  the  smaller  one 
shows  traces  of  faint  lines  recalling  those  of  other  chevrotains,  and 
these  are  more  strongly  marked  in  the  younger  animals.  I  have 
been  unable  to  find  any  account  of  the  pattern  of  the  very  young 
individuals,  but  it  is  highly  probable  that  it  is  spotted  or  striped. 

In  the  Bactrian  camel,  the  dromedary,  and  in  their  American 
allies,  the  wild  vicugna  and  huanaco,  and  the  domesticated  llama 
and  alpaca,  the  young  are  rather  paler  and  more  uniformly  coloured 
than  the  adults,  but  resemble  them  very  closely. 

If  we  turn  now  to  the  non-ruminant,  cloven-footed  Ungulates,  we 
find  some  more  cases  of  differences  between  the  young  and  the  adults 
which  are  not  readily  explained  as  direct  adaptations  for  protection. 
In  all  the  true  wild  swine  the  young  are  paler  and  pinker  than 
the  adults,  in  which  there  is  almost  always  much  dark  brown  and 
black.  The  little  pigs  are  pale  or  reddish-  brown,  and  are  marked  with 
longitudinal  rows  of  stripes,  rather  faint  and  irregular,  and  partly 
broken  into  spots.  So  also  the  young  of  the  pigmy  hog,  the  river-hogs 
and  the  wart-hogs  are  striped.  Certainly  these  animals  haunt  ground 
where  a  striped  pattern  might  aid  in  making  them  less  visible,  but 
the  stripes  are  faint,  and  not  sufficiently  clearly  marked  on  the  ground 
colour  to  have  much  effect,  whilst  the  parents  guard  their  young 
with  so  great  devotion  and  with  so  powerful  weapons  that  the  little 
pigs  have  no  need  of  concealment.  It  is  much  more  probable  that 
this  is  another  example  of  natural  growth  pattern.  The  curious 
babirussa  of  Celebes  is  uniformly  coloured  in  the  young  and  in  the 
adult,  and  the  American  peccaries  have  the  same  pattern  when 
young  and  adult. 

The  hippopotamus  is  self-coloured,  and  its  young  differ  from  it 
only  in  being  much  paler  and  pinker. 

Among  the  Odd-toed  Ungulates,  the  tapirs,  rhinoceroses  and 
horses,  it  is  only  the  tapirs  that  present  a  striking  case  of  difference  in 
pattern  between  young  and  adults.  The  full-grown  American  tapirs 
(see  Plate  VI,  p.  94)  are  nearly  uniformly  coloured,  dark  grey-brown 
or  black  above,  a  little  lighter  below,  but  with  a  white  line  round 
the  edge  of  the  shell  of  the  ear.  The  Malay  tapir  has  the  head, 
orequarters  and  legs  very  dark  brown  to  black,  but  the  whole  of  the 


94  CHILDHOOD  OF  ANIMALS 

hinder  part  of  the  body  above  and  below  is  white  and  there  is  the 
same  rim  of  white  round  the  ears.  There  is  no  difference  in  the  colora- 
tion of  the  sexes.  The  dull  coloration  of  the  American  animal, 
with  its  counter-shading,  may  well  suit  the  muddy  edges  of  the 
rivers  and  lakes  and  marshes  it  inhabits,  whilst  the  black  and  white 
of  the  Malay  species  is  a  good  example  of  ruptive  pattern,  and  when 
the  animal  is  lying  amongst  the  boulders  at  the  edge  of  a  river  in  the 
tropical  sunlight,  is  said  to  be  extremely  difficult  to  see.  But  the 
young  tapirs,  both  in  America  and  Asia,  follow  their  parents  closely, 
and  share  their  surroundings,  and  yet  are  amongst  the  most  vividly 
patterned  of  living  animals.  Their  dark  bodies  are  profusely 
striped  and  spotted  with  white,  the  stripes  and  the  rows  of  spots 
being  arranged  longitudinally  like  those  of  young  pigs,  and  being 
extremely  alike  in  all  the  species.  I  think  that  it  cannot  be  doubted 
but  that  this  infantile  pattern  (which  is  lost  in  a  few  months)  is  a 
natural  growth  pattern.  Its  similarity  in  American  and  Malay 
forms,  which  are  so  unlike  as  adults,  points  to  such  an  explanation 
being  correct. 

In  the  several  species  of  rhinoceros  the  coloration  is  nearly 
uniform,  and  the  young  differ  very  little  from  the  adults,  except  that 
they  are  more  hairy  and  paler.  The  thick  hide  reveals  its  com- 
posite or  tessellated  structure,  not  by  differences  of  colour,  but  by 
differences  of  texture,  being  broken  up  in  the  Indian  animals  into 
great  masses,  like  armour-plates,  separated  by  more  flexible  grooves. 
The  continuous  barrel-shaped  area  from  behind  the  shoulders  to 
the  hind- legs,  together  with  the  plate  covering  the  rump,  correspond 
rather  closely  with  the  region  that  is  white  in  the  Malay  tapir.  In 
the  young  African  rhinoceros  there  are  hoop-like  ridges  over  the 
back  and  flanks,  at  first  sight  suggesting  that  the  ribs  are  showing 
through  the  skin,  and  which,  if  they  happened  to  be  expressed  in 
differences  in  colour,  would  transform  the  animal  into  a  vividly 
patterned  creature.  In  the  African  and  the  Indian  species  alike 
the  hide  is  marked  with  a  series  of  bosses  and  hexagonal  areas  which 
again  only  lack  differences  of  colour  to  become  a  conspicuous 
pattern. 

Except  that  foals  are  rather  more  lightly  coloured  than  adults 
and  frequently  have  a  continuous  mane  of  short  erect  hair 
running  along  the  middle  line  of  the  back,  young  horses,  asses  and 
zebras  differ  very  little  from  their  parents  in  coloration  and  pattern. 
Spots,  dapplings  and  stripes  are  extremely  common  ;  if  they  are 
present  in  the  adults,  they  are  always  present  in  the  foals,  and  not 


PLATE  VI 

AMERICAN  TAPIR  AND  YOUNG 


94  CHIT 

of  the  I  .re  is  the 

Then  :0ra- 

th<  dull  c 

.g,   may  well  suit  1 
marshes  it  inhabit: 
is  a  good  example  of  ru- 
ing amongst  the  boulder-  at  i  the 
light,  is  said  to  be  extrem* 
ipirs,  both  in  America  and  Asia,  foil 
Mie^r  surroundings,  and  yet  area? 
•d    of   living   animals.     Their    dark 

^ed  and  spotted  with  wl  pots 

g  arranged  lonr.  }. 

emery  alike  in  ai  •     '  bted 

but  that  this  isftRjOY  (l/7\  >UHJ/T  //OlflHMA  ,  js  a 

natural  growth  pa^ 
forms,  which  an 
being  correct. 

In  the  several    sr  irly 

uniform,  and  th-  that 

they  are  more  hairy  and  j  ihick  h  com- 

posite or  tessellated  structure,  not  by  differences  of  colour,  but  by 
differences  of  texture,  being  broken  up  in  the  Indian  animals  into 
great  masses,  like  armour-plates,  separated  by  more  flexible  groj 
The  continuous  barrel-shaped  area  from  behind  the  shoulders  to 
the  hind- legs,  together  with  the  plate  covering  the  rump,  correspond 
rather  closely  with  the  region  that  is  white  v  tapir.  In 

the  young  African  rhinoceros  there  are  he  the 

back  and  flanks,  at  first  sight  suggi  bowing 

through  the  skin,  and  which,  ii 
differences  in  colour,  would  tn, 
patterned  creature.  In  the  Ai 

the  hide  is  marked  with  a  se;  iich 

again  only  lack  differences  of  picuous 

pattern. 

Except  that  foals  are  rather  mo:  -han  ad 

and   frequently    have    a    conti  ct    hair 

:ng  along  the  middle  line  o 

:.ffer  very  little  from  the,  pattern, 

iapplings  and  stripes  ar 
pres  <Q  adults,  they  are  alwa  als,  and 


COLOURS  AND  PATTERNS  OF  MAMMALS      95 

infrequently  traces  of  them  occur  in  foals  and  fade  out  when  the 
colouring  of  the  adult  has  been  reached.  It  is  difficult  to  resist 
the  conclusion  that  a  striped  pattern  is  primitive  in  the  group  and 
represents  a  natural  growth  pattern  which  is  in  course  of  oblitera- 
tion. Grevy's  zebra  is  the  most  completely  striped  of  all  the 
animals  in  the  group,  and  the  other  zebras  show  a  gradual  transition 
to  the  unstriped  donkeys,  some  of  the  stripes  fading  out  and  ap- 
pearing only  as  shadow  stripes,  the  stripes  on  the  legs  and  under  side  of 
the  body  disappearing  next,  until  the  quagga  pattern  is  reached,  an 
animal  which  was  not  much  more  marked  than  many  donkeys.  When 
zebras  are  crossed  with  horses,  the  stripes  are  more  numerous  even 
than  in  the  Grevy  zebra,  but  are  extremely  faint.  When  they 
are  crossed  with  donkeys,  the  stripes  are  more  numerous  than  in 
donkeys  and  very  brilliant,  but  less  numerous  than  in  zebras. 

The  conies  or  hyraxes  resemble  their  parents  in  coloration  very 
closely,  but  are  generally  rather  darker,  and  the  young  of  different 
species  are  more  alike  than  the  adults. 

Young  elephants  are  lighter  in  colour  and  much  more  hairy 
than  the  adults. 

Nearly  all  the  Rodents  are  quietly  coloured  creatures  with  little 
or  no  difference  in  pattern  between  the  males  and  females.  They 
are  the  prey  of  many  enemies  and  have  little  powers  of  defence. 
They  are  disposed  to  avoid  daylight,  coming  out  just  before  dusk 
and  again  in  the  very  early  morning  about  dawn.  Their  subdued 
hues  suit  their  habits.  They  are  usually  self-coloured  with  more 
or  less  of  counter-shading.  A  few  are  striped  or  spotted,  the  stripes 
or  rows  of  spots  always  being  arranged  along  the  length  of  the  animal. 
Some  of  them,  however,  and  particularly  the  squirrels,  are  vividly 
coloured,  the  colours -being  in  great  masses  or  patches.  There  are 
usually  two  moults  in  the  year,  the  winter  pelage  being  duller  and 
less  brightly  patterned,  whilst  the  vivid  colours  are  assumed  for  the 
breeding  season.  The  young  are  often  born  in  underground  nests, 
in  hollow  trees,  or  in  other  dark  and  well-concealed  places,  and 
those  that  are  produced  in  such  nurseries  are  very  immature,  naked 
and  blind.  On  the  other  hand,  if,  as  in  the  hare,  the  young  are 
born  in  the  open  fields,  and  have  to  run  the  danger  of  being  dis- 
covered by  enemies,  they  come  into  the  world  in  a  more  mature  con- 
dition, able  to  see,  and  clad  with  fur.  When  the  first  coat  of  fur 
has  been  gained,  it  is  striped  like  that  of  the  adult,  in  the  striped 
forms  ;  in  others  it  is  a  paler  imitation  of  the  adult  pattern. 

The  Marsupials  are  still  more  quietly  coloured  than  rodents,  a 


96  CHILDHOOD  OF  ANIMALS 

certain  amount  of  counter-shading  being  the  chief  variation  in  the 
general  clothing  of  dark  grey  or  brownish  fur,  but  a  few  like  the 
spotted  dasyures  and  the  striped  Tasmanian  wolf  have  special 
patterns.  The  sexes  are  always  alike,  and  the  young,  which  are 
born  as  naked  and  quite  immature  embryos,  acquire  the  pattern  of 
the  parents  as  soon  as  they  become  clothed  with  fur. 

If  we  consider  the  patterns  of  mammals  as  a  whole,  it  is  plain  that 
the  simplest  and  most  primitive  types  consisted  of  spots,  and 
that  these  were  the  expression  of  the  tessellated  or  particulate 
character  of  the  skin.  In  the  natural  course  of  growth  these  spots 
may  expand  into  short  stripes,  or  they  may  fuse  to  form  bands 
running  hoop  wise  across  the  body,  or  along  its  length.  If  there  is 
a  pattern  of  this  kind  in  the  adult,  it  is  always  present  in  the  young. 
Undoubtedly  it  must  often  aid  in  making  the  young  animals  or 
the  adults  invisible  as  they  lie  in  the  dappled  shadow  of  leaves, 
but  the  pattern  occurs  so  often,  in  so  many  different  kinds  of  animals, 
living  under  so  different  conditions,  that  although  it  may  have  been 
retained  because  it  was  useful,  it  does  not  seem  probable  that  its 
usefulness  is  the  direct  cause  of  its  origin.  Very  often  the  primitive 
spots  or  stripes  are  replaced  in  the  adult  by  an  even  tone,  marked 
only  by  counter-shading,  and  sometimes  this  monotonous  tint 
appears  even  in  the  first  coats  of  the  young.  The  fact  that  it  so 
often  replaces  a  primitive  livery  of  spots  would  seem  to  show 
that  it  is  of  later  origin,  a  more  highly  developed  kind  of  pattern. 
Lastly,  it  very  frequently  happens  that  instead  of  a  monotonous 
shade,  the  body  is  marked  by  vivid  patches  of  light  and  shade,  or 
of  colour,  over  regions  that  do  not  seem  to  correspond  with  structural 
differences  of  the  body.  These  showy,  conspicuous  patterns  are 
often  ruptive,  and  may  serve  for  concealment  by  breaking  up  the 
natural  outlines  of  the  animals.  When  they  are  present,  they  are 
generally  more  strongly  marked  in  the  males  than  in  the  females, 
and  they  replace  either  the  monotonous  or  spotted  or  striped 
pattern  of  the  young. 

The  changes  from  juvenile  to  adult  patterns  are  frequently 
abrupt  and  are  associated  with  the  natural  autumn  or  spring 
moult.  When  the  young  animals  become  nearly  full  grown  in  one 
season,  they  appear  first  in  the  rough  and  plainer  winter  pelage  ; 
when  their  youth  lasts  longer,  it  is  not  until  the  moult  after  the  first 
winter  that  they  assume  the  pattern  of  the  adult. 


CHAPTER  VII     > 
COLOURS  AND  PATTERNS  OF  YOUNG  BIRDS 

THE  complicated  changes  in  the  outer  coverings  of  mammals  enable 
us  to  understand  the  still  more  complicated  changes  in  birds. 
Primitive  mammals  appear  to  have  been  spotted  or  striped,  marked 
with  patterns  that  were  the  expression  of  the  nature  of  their  skin, 
and  of  the  natural  processes  of  growth.  These  simple  patterns  were 
replaced  by  patterns  of  a  higher  grade,  first  by  a  process  merely  of 
obliterating  them,  then  by  changing  them  still  further  by  the 
development  of  counter-shading,  of  secant  and  ruptive  marks  that 
disguised  the  natural  shape,  and  of  various  exuberances  of  ornamenta- 
tion. In  a  very  large  number  of  cases  the  primitive  growth  patterns 
are  repeated  in  the  young  ;  sometimes  these  have  disappeared  even 
from  the  young,  which  start  life  in  a  garb  of  the  second  grade,  and 
acquire  as  they  become  adult,  and  especially  if  they  are  males,  the 
highest  and  most  specialised  kinds  of  coloration. 

Feathers  are  even  more  important  to  birds  than  fur  is  to  mammals. 
Their  arrangement,  colour  and  patterns  make  up  the  greater  part  of 
the  appearance  that  a  bird  presents  to  the  world,  to  its  friends  or  to 
its  enemies  ;  the  body  of  a  plucked  bird  has  lost  the  characteristic 
size,  shape  and  appearance  to  an  extent  that  is  almost  grotesque. 
The  down  and  contour  feathers  retain  the  internal  heat  of  the  living 
body,  a  necessary  protection  as  the  blood  of  birds  is  hotter 
than  that  of  mammals  and  as  their  physiological  processes  are  more 
active.  The  quills  of  the  wings  and  tail  form  the  light  and  strong 
expanses  which  are  used  in  flight.  A  feather  is  a  more  elaborate 
organ  than  a  hair,  and  there  are  many  kinds  of  feathers,  several 
kinds  of  plumage  and  a  very  elaborate  system  of  moulting. 

The  most  characteristic  feathers  are  the  large  quills  which  lie  in  a 
single  row  along  the  outer  edge  of  the  joints  of  each  wing  and  are 
disposed  fan  wise  on  the  tail.  These  are  found  in  all  birds  ;  their 
quite  obvious  presence  in  the  flightless  ostrich  shows  that  that  bird 
and  its  allies  have  lost  a  power  of  flight  which  they  once  possessed,  and 
they  can  be  identified  even  in  penguins.  Brush  turkeys  are  the 

C.A.  97  G 


98  CHILDHOOD  OF  ANIMALS 

only  birds  in  which  they  are  so  fully  formed  at  the  time  of  hatching 
that  they  can  be  used  for  flight  at  once,  but  they  appear  very  quickly 
in  all  young  birds  and  can  often  be  counted  long  before  the  chicks 
have  left  the  egg.  Quills  are  usually  replaced  once  a  year.  Some 
water-fowl  shed  them  all  at  once,  and  in  their  unhappy  flightless 
period  have  to  hide  in  the  reeds  in  some  sheltered  corner  of  a  lake, 
an  easy  prey  to  any  foe  that  discovers  them  in  their  day  of  peril.  In 
most  birds  they  are  shed  and  replaced  in  pairs,  so  that  at  any  time 
there  are  not  more  than  one  pair  in  the  wings  and  one  pair  in  the  tail 
out  of  action,  and  there  are  always  enough  for  flight  to  take  place. 

Besides  the  quills,  there  are  two  kinds  of  feathers,  more  or  less 
corresponding  with  the  fur  and  the  under-fur  of  mammals.  There 
are  the  contour  feathers  which  make  up  the  greater  part  of  the 
covering  of  the  body,  giving  that  not  only  its  shape  but  most  of  its 
colour  and  pattern,  and  forming  the  decorative  plumes  on  head 
and  wings  and  tail.  They  are  not  spread  evenly  over  the  surface 
of  the  body,  but  are  inserted  on  special  regions,  with  naked  spaces 
between  them  in  all  except  a  very  few  birds,  and  even  in  some 
of  these,  such  as  the  ostrich,  they  are  arranged  on  definite  tracts 
in  the  young  bird,  although  they  are  evenly  distributed  in  the  adult. 
Secondly,  there  are  the  softer,  more  tuft-like  down  feathers,  corre- 
sponding with  the  under-fur  of  mammals,  and  like  that  found  most 
abundantly  in  creatures  which  require  special  protection  from  cold. 
These  may  be  attached  to  the  interspaces  between  the  contour 
feathers,  or  they  may  be  distributed  all  over  the  bird,  or  they  may  be 
found  only  on  the  feather-tracts,  concealed  by  the  other  feathers. 
It  seems  most  probable  that  these  down  feathers  are  a  later  develop- 
ment and  are  degenerate  contour  feathers,  the  only  purpose  of  which 
is  to  thicken  the  warm  covering  of  the  body. 

There  are  many  reasons  why  birds  should  moult,  and  from  time  to 
time  renew  their  outer  garment,  which  is  at  once  an  ornament,  a 
protection  and  a  most  useful  organ.  Feathers  are  fragile  and  quickly 
become  frayed,  broken  or  worn.  In  a  few  cases  the  wearing  of  the 
tips  of  the  feathers  at  first  smartens  the  plumage.  The  throat  of  the 
sparrow  is  dingy  in  winter,  mottled  with  brown  and  black,  but  as  the 
tips  of  the  feathers  wear  off  they  reveal  the  brilliant  black  band 
which  decorates  the  bird  in  spring.  So  also  the  rosy  pink  of  the 
linnet's  breast  in  spring  appears  only  when  the  dull  tips  of  the  winter 
feathers  have  been  worn  off.  In  some  birds,  this  accident  has  been 
transformed  to  a  system.  Many  brightly  coloured  ducks  acquire 
their  brilliant  breeding  plumage  in  autumn,  and  yet  in  spring,  when 


COLOURS  AND  PATTERNS  OF  BIRDS         99 

courtship  begins,  become  still  more  brilliant,  not  by  a  new  moult,  but 
by  discarding  the  pale  tips  of  their  bright  feathers.  Such  devices 
are  on  the  whole  rare  and  at  the  best  are  expedients  which  make 
the  feathers  last  a  little  longer.  Sooner  or  later,  if  the  plumage  is 
to  retain  its  usefulness  or  to  alter  its  appearance,  it  must  be 
changed  by  a  moult. 

The  moults  are  sometimes  associated  with  changes  of  colour  and 
pattern,  and  sometimes  merely  lead  to  the  restoration  of  the  dis- 
carded dress  in  a  fresh  condition.  When  there  is  no  brilliant 
breeding  plumage,  and  especially  when  both  males  and  females  are 
sad-coloured  and  much  alike,  the  moults  may  be  numerous  in  a 
single  year  and  yet  the  coloration  remain  uniform.  Such  dismal 
creatures  are  exceptions.  Most  birds  are  brilliant  for  a  part  of  the 
year,  sometimes  only  for  a  few  weeks  of  courtship,  sometimes  for  the 
greater  part  of  the  year,  and  sometimes  for  the  whole  year  round. 
The  different  plumages  that  birds  may  assume  successively  as  the 
results  of  moults  are  so  varied  that  it  is  not  easy  to  get  a  clear 
picture  of  them.  I  must  begin  by  enumerating  them  and  by  giving 
some  examples  of  them. 

First  of  all,  the  chicks  may  be  clad  in  a  coating  of  down.  This  may 
be  replaced  by.  one  or  more  successive  immature  plumages  and  these 
may  be  followed  by  different  kinds  of  adult  plumages.  The  adult 
plumage  may  be  the  same  all  the  year  round,  and  in  that  case  the 
males  and  females  may  be  alike  or  different.  There  may  be  a 
specially  brilliant  plumage  assumed  in  the  breeding  season,  by  the 
males  only,  or  by  both  males  and  females.  When  the  breeding 
season  is  over,  the  brilliant  plumage  may  be  lost,  the  birds  passing 
into  what  is  now  known  as  "  eclipse  "  plumage,  and  this  may  be 
identical  or  different  in  the  males  and  females.  The  eclipse  plumage 
is  very  often  seen  in  winter,  as  spring  and  early  summer  are  the 
breeding  seasons,  and  for  that  reason  it  is  sometimes  spoken  of  as 
the  "  winter  "  plumage.  "  Winter  "  plumage,  however,  is  a  mis- 
leading term,  because  it  extremely  often  happens  that  it  is  passed 
through  long  before  winter  begins.  Some  examples  will  make  the 
matter  clearer.  In  winter,  the  common  lapwing  or  peewit  is  a  dull- 
coloured  bird,  with  a  very  short  crest,  a  brownish  head,  a  white  or 
grey  neck,  and  with  the  back  mottled  with  dark  brown.  The  males 
and  females  differ  very  little.  In  early  spring  a  moult  takes  place. 
The  male  becomes  resplendent,  with  a  long  crest,  and  a  body  shining 
with  metallic  olive-greens  and  purples,  steely-blue  and  ruddy-brown, 
picked  out  with  vivid  black  and  white.  The  female  is  a  less 


loo  CHILDHOOD  OF  ANIMALS 

brilliant  copy  of  the  male,  with  a  shorter  crest  and  a  dimmer  lustre. 
When  the  breeding  season  is  over,  there  is  a  second  moult  and  both 
sexes  appear  in  the  winter  garment  of  repentance.  In  this  case  the 
"  eclipse  "  plumage  coincides  with  winter,  and  the  breeding  plumage 
with  summer.  The  next  example  I  shall  take  is  that  of  a  very 
different  kind  of  bird.  The  beautiful  little  passerine  bird  known 
as  the  superb  tanager,  and  often  seen  in  zoological  gardens,  is  a 
jewel  of  colour,  shining  with  green,  orange  and  shades  of  purple  and 
blue,  the  female  being  only  less  brilliant  than  the  male.  These  re- 
splendent garbs  are  the  breeding  plumage  and  are  retained  for 
rather  more  than  half  the  year.  There  is  then  a  moult,  and  both 
males  and  females  pass  into  a  dull  brown  eclipse  plumage  in  which 
it  is  very  difficult  to  distinguish  them.  The  contrast  is  not  always  so 
great  as  in  the  two  cases  I  have  taken,  and  it  is  more  common  for  the 
female  to  remain  comparatively  dull  even  after  moulting  into  the 
breeding  plumage.  Nor  is  the  division  of  the  year  between  the  two 
plumages  usually  so  regular.  A  dull  eclipse  livery  for  both  sexes  for 
the  greater  part  of  the  year,  with  a  bright  breeding  dress  at  least  for 
the  male  for  a  smaller  part  of  the  yeaj,  is  the  most  common  state  of 
affairs. 

No  set  of  birds  display  more  brilliant  patterns  and  fantastic  decora- 
tions than  are  to  be  found  amongst  ducks,  where,  however,  the  drakes 
are  bright  whilst  the  females  show  little  colour  change.  This 
gay  plumage  is  found  in  the  breeding  season  in  its  most  brilliant 
form,  but,  unlike  the  lapwings,  drakes  may  retain  it  for  the  greater 
part  of  the  year.  When  the  cares  of  married  life  are  over,  they 
change  into  a  dull  eclipse  livery,  but  instead  of  retaining  that  until 
next  spring,  they  put  it  off  again  after  a  few  weeks  or  months,  and  by 
a  new  moult  again  put  on  the  brilliant  colours,  although  the  whole 
winter  has  to  be  spent  before  spring  recalls  them  to  love.  In  some 
ducks,  especially  those  of  South  America,  the  eclipse  plumage  either 
does  not  occur,  or  lasts  so  short  a  time  that  it  has  not  been  noticed, 
or  is  merely  a  paler  copy  of  the  usual  garb.  In  many  of  the  game  birds 
there  is  the  same  double  moult,  but  the  eclipse  plumage  is  shown 
only  by  a  few  dull  feathers,  visible  to  the  expert,  but  making  little 
difference  in  the  general  appearance  of  the  bird.  Amongst  these, 
also,  the  males  have  the  resplendent  colours.  Lastly,  there  are  a 
number  of  birds,  such  as  parrots  and  kingfishers,  in  which  there  is  no 
change  throughout  the  year,  but  the  most  brilliant  colours  are  re- 
tained permanently,  and  when  the  single  annual  moult  occurs  an 
identical  livery  is  assumed.  In  these  birds  the  males  and  females 


COLOURS  AND  PATTERNS  O^JSIRDJS-  'j  $ 


are  both  brilliantly  coloured,  usually  alike,  although  there  is  the 
odd  case  of  the  Eclectus  parrots,  that  I  have  already  mentioned, 
where  one  sex  is  green,  the  other  scarlet. 

When  birds  are  hatched,  some,  like  ducklings  and  chickens,  are  born 
with  a  warm  coating  of  down  feathers,  and  are  able  to  run  about, 
see  and  peck  almost  as  soon  as  their  coats  are  dry.  Others,  such 
as  the  chicks  of  most  of  the  familiar  singing  birds,  come  into 
the  world  helpless,  blind  and  naked,  entirely  dependent  on  the 
care  of  their  parents.  We  have  seen  that  among  mammals  the  con- 
dition of  the  young  at  birth  depends  on  the  habits  rather  than  on  the 
families  to  which  the  animals  belong.  The  older  naturalists,  misled 
by  seeing  the  condition  of  the  young  nestlings  alike  in  many  large 
groups,  thought  that  it  depended  more  on  relationship  than  on  habits, 
but  there  are  so  many  differences,  among  nearly  allied  birds,  that  it 
seems  to  be  a  simple  adaptation  to  the  conditions.  If  the  eggs  are  laid 
in  safe,  inaccessible  places,  as  in  nests  on  trees,  or  in  holes,  the  young 
are  usually  helpless.  If  they  are  laid  where  the  young  chicks  may 
have  to  take  refuge  in  the  water,  or  to  hide  in  the  herbage  at  any 
moment,  they  are  hatched  only  when  the  chicks  are  able  to  swim  or  to 
run  about.  When  the  young  are  born  in  a  precocious  condition,  the 
eggs  are  larger  in  proportion  to  the  size  of  the  parents  and  take  longer 
to  incubate.  The  average  time  of  incubation  is  from  eighteen  to 
twenty-six  days  ;  humming-birds,  which  lay  small  eggs  even  in 
proportion  to  their  small  size,  brood  over  them  for  less  than  a  fort- 
night, and  the  newly  hatched  young  are  naked  and  helpless. 
Ostriches  and  their  allies  lay  eggs  which  are  very  large  even  in 
proportion  to  the  large  size  of  the  parents,  and  when  the  chicks  come 
out  they  are  able  to  run  about  almost  at  once.  At  the  ostrich 
farm  of  Mr.  Carl  Hagenbeck,  in  Hamburg,  I  have  seen  the  actual 
hatching  of  young  ostriches  from  eggs  that  had  been  brooded  in  an 
incubator.  At  the  right  time,  when  the  chick  had  begun  to  break 
its  way  through  the  hard  shell,  the  operator  helped  the  process,  the 
little  bird  came  out,  and  in  a  few  minutes  was  able  to  stand  up  and 
take  its  first  meal  of  pounded  shell,  whilst  in  less  than  an  hour  it  was 
running  about  on  the  warm  sand  of  the  floor  of  the  nursery  prepared 
for  it,  and  taking  its  food  without  any  assistance.  So  also  young 
emus,  rheas  and  cassowaries,  tinamous,  all  the  game  birds,  rails, 
cranes  and  bustards  are  clothed  and  active  when  they  are  hatched, 
and  are  able  to  follow  their  parents  on  the  ground  almost  at  once. 
The  sand-grouse,  which  have  the  habits  of  game  birds,  although 
related  to  the  pigeons,  are  born  in  an  active  condition.  Shore  and 


\\tpz  CHILDHOOD  OF  ANIMALS 

marsh  birds,  such  as  plovers,  curlews,  avocets  and  gulls,  all  oi  which 
lay  their  eggs  on  or  near  the  ground,  have  active  young.  Rails, 
divers  and  grebes,  screamers  and  all  the  swans,  ducks  and  geese  hatch 
out  as  lively,  downy  creatures,  able  to  walk  and  run,  and  some  of 
them  able  to  swim  from  the  first.  On  the  other  hand,  penguins, 
which  lay  a  single  egg  and  incubate  it  on  the  feet,  hatch  out  a 
blind  and  naked  chick.  Gannets  and  cormorants  and  petrels,  which 
lay  in  holes  in  the  rocks  or  in  trees,  all  the  hawks,  eagles  and  owls, 
kingfishers,  swifts  and  woodpeckers,  pigeons,  parrots  and  cuckoos, 
and  all  the  perching  and  singing  birds,  hatch  out  their  young  in 
protected  places  and  in  a  helpless,  frequently  naked  condition. 

Whether  newly  hatched  birds  already  possess  a  covering  of  feathers 
or  have  to  wait  days  or  weeks  to  acquire  it,  the  first  plumage  is 
usually  very  different  from  that  of  the  adult,  and  a  number  of 
successive  suits  may  have  to  be  put  on  before  the  full  dress  of  the 
adult  is  reached.  The  differences  are  partly  in  colour  and  partly  in 
texture. 

Although  the  first  plumage  of  nestlings  is  nearly  always  soft  and 
downy,it  seldom  corresponds  with  the  down  feathers  of  the  adult, but 
usually  with  the  contour  feathers.  One  of  the  naturalists  on  the  staff 
of  the  British  Museum,  Mr.  W.  P.  Pycraft,  has  worked  out  the  nature 
of  the  feathers  in  a  great  many  young  birds.  He  has  shown  that 
although  a  newly  hatched  owl  and  hawk  are  both  clad  in  a  soft 
white  downy  plumage,. the  individual  feathers  composing  the  covering 
are  different  in  the  two  cases.  In  the  owl  each  down  feather  occupies 
the  place  of  a  future  contour  feather,  but  neither  in  the  embryo  nor 
in  the  adult  are  true  down  feathers  ever  developed.  Each  of  these 
first  feathers  of  the  owl  is  shaped  like  the  umbel  of  a  flower,  or  like 
the  ribs  of  an  umbrella  that  has  been  blown  inside  out,  and  which  has 
had  the  stick  cut  away  ;  there  is  no  central  axis  or  stem,  but  the  circle 
of  little  barbs  all  arise  from  the  same  point.  In  a  very  short  time 
this  first  plumage  is  moulted  off,  and  replaced  by  a  second  set  of 
downy  feathers.  These  still  occupy  the  place  of  the  contour 
feathers,  but  they  are  differently  shaped  ;  each  is  like  a  true  feather 
and  has  a  central  stem  or  axis  to  which  the  feathery  barbs  are 
attached.  In  late  autumn  of  the  first  year  the  second  down  plumage 
is  moulted,  and  the  contour  feathers  of  the  adult  take  their  place. 
In  the  brush  turkeys,  or  mound  builders,  where  the  eggs  are  very 
large,  and  where  the  young  are  hatched  in  an  advanced  condition,  the 
first  set  of  down  feathers,  corresponding  with  that  of  the  owls,  is 
formed  and  shed  before  the  chick  is  hatched,  and  the  second  down 


COLOURS  AND  PATTERNS  OF  BIRDS        103 

plumage  is  well  formed  at  the  time  of  hatching.  In  most  birds 
this  first  plumage  has  been  suppressed  entirely.  In  some  of  the 
ducks,  traces  of  the  first  plumage  are  found  ;  in  most  of  them,  as  in 
all  the  game  birds,  only  the  second  plumage  appears.  In  the 
nestling  pigeon,  even  the  second  plumage  is  degenerate  and  appears 
only  as  a  few  scattered  thread-like  hairs,  whilst  this  nakedness  is 
carried  still  further  in  nearly  all  the  singing  and  perching  birds.  In 
kingfishers,  hornbills,  swifts  and  humming-birds,  there  is  no  down 
either  in  the  nestling  or  in  the  adult,  and  the  final  contour  feathers 
appear  early,  so  that  the  nestlings  look  like  small  spiny  hedgehogs. 
In  hawks,  eagles  and  vultures,  on  the  other  hand,  although  there  is 
a  thick  coating  of  down,  it  is  composed  almost  entirely  of  feathers 
which  are  afterwards  replaced  by  the  true  down  feathers  of  the  adult ; 
whilst  in  cormorants,  the  nestling  downy  plumage  is  altogether  a  fore- 
runner of  the  adult  downy  feathers. 

It  is  not  easy  to  form  a  general  picture  of  the  differences  in  colora- 
tion between  young  birds  and  adults.  The  number  of  species  of 
birds  is  enormous,  and  although  naturalists  have  devoted  them- 
selves to  collecting  examples  in  the  field  and  forest,  and  to  studying 
them  in  museums,  with  the  greatest  patience  and  enthusiasm,  there 
remain  many  gaps  in  our  knowledge,  especially  as  to  the  changes 
that  individuals  pass  through  in  the  course  of  their  lives.  Nature 
seems  to  have  lavished  colour  and  pattern  on  the  group,  and  to  be 
displaying  her  eccentricities,  her  exuberance  and  her  whimsicalities, 
rather  than  pursuing  her  usual  orderly  course.  None  the  less  it  is 
just  possible  to  get  an  idea  of  a  general  course  of  events,  an  idea, 
however,  which  must  not  be  taken  too  rigidly,  for  there  are  probably 
exceptions  which  cannot  readily  be  brought  into  harmony  with  it. 

The  colours  of  young  birds  are  never  brighter  than  those  of  their 
parents.  There  is  one  apparent  exception  to  this,  but  it  applies  to 
the  skin  and  not  to  the  feathers.  The  naked  and  helpless  nestlings 
which  are  reared  in  trees,  in  holes,  and  other  rather  dark  and  well- 
concealed  places,  are  provided  with  heads  that  seem  much  too  large 
for  their  bodies,  and  with  mouths  that  seem  too  large  for  the  heads. 
The  mouths  are  actually  enormous,  and  when  the  parent  birds  come 
carrying  their  spoil  of  worms  or  grubs,  the  huge  opening  seems  even 
larger  than  it  is,  because  it  is  marked  at  the  sides  with  bright  patches 
of  colour,  sometimes  yellow  as  in  the  starling,  sometimes  white.  The 
inside  of  the  mouth  is  also  brightly  coloured,  yellow  perhaps  being 
the  most  common  tint,  as  in  larks  and  thrushes,  but  red  and  yellow 
in  some  of  the  titmice.  These  colours  fade  away  as  the  young  birds 


104  CHILDHOOD  OF  ANIMALS 

grow,  and  it  is  probable  that  they  serve  as  guides  to  the  mother.  A 
light  may  be  unnecessary  to  find  the  way  to  one's  own  mouth,  but  a 
little  help  to  the  mouths  of  others  may  not  be  amiss. 

The  colour  and  pattern  of  the  first  coat  of  downy  feathers,  whether 
that  appears  before  hatching  or  is  acquired  in  a  few  days,  never  bear 
any  intelligible  relation  to  the  coloration  of  the  adult  plumage. 
Very  often  indeed  the  colour  is  uniform,  varying  from  pure  white 
through  dusky  yellows  and  greens  to  pure  black,  and  he  would  be  an 
ingenious  person  who  could  trace  any  connection  between  the  shades 
of  the  downy  coat  and  the  habits  and  surroundings  of  the  young. 
The  ostrich  and  the  apteryx,  the  largest  and  the  smallest  of  the 
flightless  birds,  are  uniformly  coloured,  the  latter  being  of  a  dusky 
grey,  the  former  grey  with  faint  traces  of  the  striping  and  mottling 
seen  in  the  other  ostrich-like  birds,  and  appearing  as  if  the  marks  had 
been  washed  out.  Young  penguins  all  wear  a  thick  coat  of  down 
(see  Plate  VII),  which,  although  it  may  be  a  little  lighter  in  front 
and  a  little  darker  on  the  back,  is  evenly  coloured  ;  in  some,  like  the 
common  rock-hoppers  most  frequently  seen  in  zoological  gardens, 
being  very  dark  brown,  almost  black,  in  others  being  dark  buff,  light 
yellow  or  dirty  white  with  sometimes,  as  in  the  emperor  penguins, 
black  on  the  head.  Until  man  came  to  disturb  them,  penguins  had 
few  enemies  except  the  weather  in  the  great  rookeries  in  which  they 
breed  and  had  no  need  of  special  protection  from  concealing  colora- 
tion. The  downy  coat  of  the  albatross  is  sooty-brown.  Pelicans  are 
hatched  naked,  but  in  a  few  days  their  flesh-coloured  skin  is  covered 
with  a  fluffy  coat,  pure  white  in  colour.  Flamingoes  show  no  trace  of 
the  brilliant  scarlet  that  decorates  their  adult  plumage,  but  are  snowy- 
white  when  they  are  in  down.  Screamers  (Chauna)  when  they  are 
hatched  appear  in  a  uniform  coat  of  grey-brown,  a  little  yellower  on 
the  head,  and  set  off  by  the  brilliant  red  of  the  skin  round  the  eyes 
and  the  naked  legs.  Newly  hatched  swans  are  pure  white  in  some 
species,  as,  for  example,  in  the  case  of  the  very  beautiful  black-necked 
swan  (see  Plate  XI,  p.  240),  but  more  usually  they  are  yellowish. 
Some  of  the  geese  and  ducks,  particularly  the  domesticated  species, 
are  clad  in  a  monotonous  uniform  of  white,  which  may  be  pure  white, 
yellowish  or  dusky,  but  this  is  not  the  familiar  uniform  of  their  tribe. 
The  young  of  the  rails,  coots  and  moorhens  are  almost  quite  black 
when  they  are  clad  in  their  first  downy  covering.  Sometimes  there 
is  a  faint  metallic  sheen  recalling  the  vivid  colours  of  the  adults.  The 
chick  of  the  Australian  waterhen  has  its  dusky  head  just  lightened 
with  a  greenish-purple  iridescence  ;  the  black  of  the  chick  of  the 


PLATE  VII 

KING  PENGUINS  AND  YOUNG 

The  figures  to  the  left  show  the  young  in  downy  plumage, 
those  to  the  right  show  the  adult  plumage. 


CHII 

grow,  and  it 

light  may  bo  it  a 

littl  •  s  of  others  may  no! 

pattern  of  the  first  coat  Aether 

•ore  hatching  or  is  acqui  rex  bear 

relation  to  the  coloration  lumage. 

ndeed  the  colour  is  uniforir  ?u'te 

dusky  yellows  and  greens  to  pure  bl  d  be  an 

ingenious  person  who  could  trace  any  connec  a  the  shades 

ie  downy  coat  and  the  habits  and  s  the  ymmg. 

The  ostrich  and  the  apteryx,  the  »  llest  of  the 

flightless  birds,  are  uniform'  r  of  a  dusky 

grey,  the  former  gn  ling 

seen  in  the  other  irks  had 

been  washed                         MV  ^TAJ'i  of  down 

(aw  Plate       O^-JOY  a>  rjo-,n 

and  a  httle  dark*  the 

cnirijtt»(  >ens, 
JM*  ®d*  woda 


being  very  darSB*1110^  JM*  ®d*  woda  ^Rh  odj  ot  ^odi  ight 

yellow  o  »r  penguins, 

black  on  the  head.     Until  man  came  to  disturb  '-nguins  had 

few  enemies  except  the  weather  in  the  great  rookeries  in  which  they 
breed  and  had  no  need  of  special  protection  from  concealing  colora- 
tion. The  downy  coat  of  the  albatross  is  sooty-brown.  Pelicans  are 
hatched  naked,  but  in  a  few  days  their  flesh-coloured  skin  is  covered 
with  a  fluffy  coat,  pure  white  in  colour.  Flamingoes  show  no  trace  of 
the  brilliant  scarlet  that  decorates  their  adult  plumage,  but  are  snowy- 
white  when  they  are  in  down.  Screamers  (Chi-  are 

hatched  appear  in  a  uniform  coat  oi  r  on 

the  head,  and  set  off  by  the  brillian  ?yes 

and  the  naked  legs.    Newly  hatchec  ome 

species,  as,  for  example,  in  the  c? 
swan  (see  Plate  XI,  p.  240),  fr 

Some  of  the  geese  and  ducks,  p  ciesf 

lad  in  a  monotonous  unifon  liite, 

wish  or  dusky,  but  this  !  ibe. 

rig  of  the  rails,  coots  and  r 
H-y  are  clad  in  their  first  dov 

t  allic  sheen  recalling  the  v  i  v  id  colon  '  1  ts  .  The 

chic  i  Australian  waterhen  has  its  dn 

purple  iridescence  ;    the  black 


COLOURS  AND  PATTERNS  OF  BIRDS        105 

common  moorhen  has  a  greenish  lustre.  The  down  of  young  owls 
is  usually  pure  white.  In  most  of  the  birds-of-prey  the  down  is 
uniform  ;  in  ospreys  it  is  clay-coloured  ;  in  the  condor  the  head  is 
naked,  but  the  body  is  covered  after  a  few  days  with  a  thin  coat 
of  white  down.  In  vultures  it  is  usually  white,  but  may  be  yel- 
lowish or  picked  out  with  black  on  the  wings  as  in  the  American 
black  vulture,  whilst  in  most  of  the  eagles  it  is  dirty  yellow.  In 
birds  which  never  acquire  a  real  coat  of  down,  but  which  are  naked 
except  for  a  few  hair-like  tufts,  these  remnants  are  white  or  pale. 

The  down  covering  of  many  young  birds  shows  a  conspicuous 
pattern  of  either  spots  or  stripes,  spots  elongating  to  form  stripes,  or 
stripes  breaking  up  to  form  spots.  These  patterns  resemble  in  a 
most  striking  way  the  simple  growth  patterns  to  which  I  called 
attention  in  the  case  of  young  mammals.  The  arrangement  is 
usually  one  that  recalls  the  simple  kind  of  bilateral  patterns  made  by 
squeezing  ink  marks  in  folded  paper  (see  Fig.  21,  p.  65),  and  although 
the  result  may  sometimes  be  of  use  in  helping  to  make  the  young 
birds  less  conspicuous  against  the  background,  when  they  are  squat- 
ting in  the  sunlight  amidst  reeds  and  other  vegetation,  or  on  a 
pebbly  beach,  they  occur  so  constantly  in  many  different  groups  of 
different  habits  that  I  find  it  difficult  to  think  of  them  as  special 
adaptations.  They  appear  to  be  the  more  or  less  inevitable  result 
of  the  particulate  character  of  the  skin  and  of  the  mode  of  growth. 
They  have  been  retained  in  cases  where  they  are  either  useful  or 
harmless,  but  they  are  survivals  of  an  ancestral  or  primitive  con- 
dition which  have  been  preserved,  rather  than  new  creations  for  the 
special  benefit  of  their  possessors.  Moreover,  in  many  of  the  self- 
coloured  chicks  there  are  faint  indications  of  obliterated  stripes 
which  would  seem  to  show  that  the  plain-coloured  chicks  have  more 
modern  coverings  than  the  striped  and  spotted  forms. 

The  nestling  rhea  or  South  American  ostrich  (Fig.  25,  p.  107,  right- 
hand  figure)  is  covered  with  a  thick  coat  of  long  down  feathers,  dirty 
grey  on  the  head  and  under  surface,  but  with  a  long  dark  brown  patch 
on  the  neck  which  forks  over  the  wings,  and  is  continued  along  the 
middle  line  of  the  back  as  a  diamond-shaped  mark  tapering  off  towards 
the  region  of  the  tail.  On  each  side  of  this  a  broad  brown  stripe  runs 
backwards  from  the  wings  towards  the  tail,  whilst  a  second  stripe  at 
each  side  runs  along  the  outer  surface  of  the  thigh  and  leg.  These 
brown  stripes  leave  the  pale  grey  background  between  them  as 
narrow  bands.  In  the  young  emu,  the  same  general  arrangement 
of  dark  stripes  on  a  light  background  is  present,  but  the  stripes  are 


106  CHILDHOOD  OF  ANIMALS 

partly  broken  up  into  rows  of  large  spots.  In  the  cassowary,  the 
dark  stripes  are  wider  than  the  interspaces,  so  that  the  nestling  looks 
like  a  dark  bird  banded  with  white.  Grebes  nest  in  the  same  marshy 
streams  as  many  of  the  rails  and  moorhens,  but  the  down  of  the 
nestlings  is  vividly  striped,  with  dark  bands  running  along  the  body. 
The  nestlings  are  carried  by  the  mother  on  her  back,  but  so  also  are 
the  self-coloured  nestlings  of  swans. 

A  special  but  very  simple  pattern  is  found  in  many  of  the  geese, 
like,  for  instance,  the  cereopsis  goose,  the  sheldrakes  (Fig.  25,  middle 
figure)  and  the  whole  tribe  of  ducks  except  the  domesticated  breeds. 
The  ground  colour  is  a  dirty  white  and  this  is  retained  on  the  under 
surface.  The  upper  surface  of  the  head  is  dark  brown  approaching 
black,  and  this  is  carried  towards  the  tail  as  a  broad  stripe  which 
expands  to  a  diamond  shape  over  the  shoulders,  with  extensions 
running  along  the  wings,  and  broadens  out  again  towards  the  tail. 
Another  dark  band,  which  generally  meets  the  median  band,  runs 
downwards  and  backwards  along  the  outer  surface  of  the  thigh.  In 
the  sheldrakes  this  pattern  is  very  plain  and  leaves  elongated  spots 
of  the  white  ground  colour  just  behind  the  wings  and  the  insertion 
of  the  legs.  In  the  different  ducks,  the  dark  patches  and  stripes 
occupy  more  and  more  of  the  back  until  they  may  leave  the  ground 
colour  showing  only  as  a  pair  of  bright  spots  opposite  the  insertion 
of  the  legs,  and  a  less  conspicuous  pair  of  spots  opposite  the  wings 
(Fig.  25,  left-hand  figure).  Clearly,  the  geese  and  ducks  show  the 
gradual  disappearance  of  the  ancestral  striped  pattern  and  its 
replacement  by  a  nearly  self-coloured  dark  back. 

The  downy  coats  of  newly  hatched  jungle-fowl,  pheasants,  quail 
and  partridges  and  the  other  fowl-like  game  birds  show  a  simple 
growth  pattern  rather  like  that  of  the  ducks  and  geese,  and,  like 
it,  tending  to  be  smoothed  over  and  replaced  by  a  nearly  uniform 
tone.  The  ground  colour  varies  from  white  to  a  dirty  yellow  and 
remains  unaltered  over  the  lower  surface  (see  Plate  IV,  p.  69).  On  the 
head  and  back  there  is  a  dark  stripe,  expanding  to  a  diamond  shape 
between  the  shoulders,  and  running  backwards  towards  the  tail 
where  it  may  expand  again.  On  the  hinder  part  of  the  body  there 
is  a  dark  stripe  running  backwards  at  each  side,  separated  from  the 
middle  stripe  by  an  unaltered  portion  of  the  light  ground  colour. 
A  similar  dark  band  runs  across  each  wing  and  down  the  thigh.  Such 
a  pattern  appears  and  reappears  all  through  the  group,  however  the 
adults  may  differ,  but  it  fades  out,  becoming  fainter  in  the  small 
quails  and  partridges. 


COLOURS  AND  PATTERNS  OF  BIRDS        107 

Stripes,  visible  on  the  head,  but  fading  off  into  the  brownish  hue 
of  the  back,  are  found  in  the  tinamous.  Stripes  or  spots  arranged 
irregularly  or  just  suggesting  striping  appear  in  the  nestlings  of  wading 
birds,  and  in  most  of  the  gulls  (see  Plate  VIII,  p.  162)  and  terns. 

Sooner  or  later  young  birds  moult  off  their  down  if  they  have 
possessed  it,  and  acquire  a  covering  of  true  feathers.  The  feathers 


FIG.  25.  Down -plumage  Patterns.  To  the  left  a 
Summer-duck,  in  the  middle  a  Sheldrake,  and  to 
the  right  a  Rhea. 

appear  gradually,  either  on  the  naked  body  or  amongst  the  down,  and 
the  time  taken  after  hatching  to  acquire  the  first  plumage  may 
differ  much  in  very  closely  allied  birds.  The  emperor  penguin 
remains  no  more  than  four  months  in  the  down,  although  the  rather 
smaller  king  penguin  does  not  assume  its  first  true  feathers  for  nearly 
ten  months.  The  first  feathers  to  appear  are  usually  those  on  the 
wings  and  tail,  especially  in  birds  that  live  or  nest  on  the  ground  or 
near  the  water.  Young  brush  turkeys  are  able  to  fly  almost  as  soon 
as  they  leave  the  egg.  Fowls,  pheasants,  partridges,  ducks  and  geese 


io8  CHILDHOOD  OF  ANIMALS 

begin  to  have  their  wings  well  fledged  in  from  a  few  days  to  a  few 
weeks.  In  birds  that  nest  in  trees  or  holes,  or  high  above  the 
ground,  the  flight  feathers  usually  lag  behind  the  others.  The  time, 
however,  is  closely  fitted  to  the  habits  of  each  species  and  has  no 
general  relation  to  the  kind  of  bird  or  to  the  size  of  the  bird.  A 
young  Californian  condor,  one  of  the  largest  of  living  birds  and 
which  weighed  nearly  a  pound  when  it  was  newly  hatched,  was  at 
first  clad  in  a  scanty  white  down,  but  had  the  head  naked.  A  month 
later  it  was  as  large  as  a  hen,  and  covered  with  a  greyish  down,  and  it 
was  not  until  it  was  over  two  and  a  half  months  old  that  the  first 
trace  of  true  feathers  appeared  on  its  tail.  When  it  was  three  and  a 
half  months  old,  and  weighed  fifteen  pounds,  it  was  still  more  than 
half  covered  with  down.  Some  of  the  small  singing  birds,  which  are 
naked  when  they  are  hatched,  may  be  fully  fledged  in  two  or  three 
weeks. 

The  acquisition  of  a  coating  of  true  feathers,  however,  by  nc 
means  implies  that  the  young  bird  has  acquired  the  pattern  and 
colour  of  the  adult.  A  number  of  successive  moults,  occupying  one 
or  more  years,  may  have  to  be  gone  through  before  the  young  bird 
assumes  its  final  garb.  The  facts  are  bewildering  in  their  com- 
plexity and  some  of  them  are  extremely  difficult  to  place  in  an 
orderly  picture.  The  general  rule,  to  which  the  exceptions  are  ex- 
tremely rare,  is  that  the  early  plumages  of  young  birds  are  dullei 
in  colour  than  the  dullest  of  the  adult  garbs  of  their  kind  ;  that  the} 
resemble  the  young  plumages  of  allied  birds  more  closely  than  the 
various  adult  plumages  of  such  birds  resemble  each  other  ;  that  ir 
colour  they  are  extremely  often  brown,  whatever  be  the  colour  of  th< 
adult  plumages  ;  and  that  in  pattern  they  show  such  simple  growtl 
patterns  as  stripes,  spots,  bars  and  mottlings  much  more  frequentl} 
than  the  adults. 

The  most  familiar  case  of  differences  between  young  and  aduli 
plumages  is  that  when  the  sexes  differ,  the  young  are  like  the  plainei 
of  the  two  adults.  Every  one  knows  examples  of  this.  In  pheasants 
(see  Plate  IV,  p.  69)  and  fowls  the  cocks  are  amongst  the  most  resplen 
dent  of  living  creatures.  Their  heads  are  decorated  with  wattles 
combs,  coloured  patches  and  crests.  Their  plumage  shines  with  all  th<  i 
colours  of  the  rainbow,  with  green  and  gold,  purple  and  crimson,  anc 
red  and  yellow,  arranged  in  the  most  fantastic  of  patterns.  Th< 
cocks  of  different  species  are  extremely  unlike.  The  hens  ar< 
clothed  in  subdued  patterns,  simple  stripes  and  mottlings,  colour e< 
in  various  shades  of  brown,  with  at  the  most  pale  reflections  of  th< 


COLOURS  AND  PATTERNS  OF  BIRDS   109 

glories  of  their  mates.  The  hens  of  different  species  are  much  more 
alike,  so  alike  that  it  requires  attention  and  expert  knowledge  to 
distinguish  them,  whilst  the  poorest  observer  could  be  in  no  doubt 
as  to  the  specific  distinction  of  the  cocks.  The  chicks  in  their  first 
plumage  are  always  very  much  more  like  the  females  and  like  the 
corresponding  stages  in  other  pheasants,  and  here  again  it  requires 
an  expert  to  distinguish  them.  An  even  more  startling  case  of 
brilliant  males  and  dull  females  is  that  of  the  birds-of-paradise.  The 
fantastic  extravagances  of  their  plumes,  the  jewelled  splendour  of 
their  eyes  and  the  riot  of  colour  in  their  plumage  far  surpass  the 
most  glowing  imagination  of  the  artists  who  combine  all  the  shining 
products  of  the  loom  and  the  most  curious  dyes  of  the  chemist  to 
compose  the  stately  robes  of  emperors.  But  all  this  exuberance  is 
lavished  on  the  males.  The  females  have  to  be  content  with  dingy 
garbs  of  mottled  brown.  The  young  birds  are  so  like  the  females, 
and  so  like  one  another,  that  it  is  often  difficult  to  determine  the  sex 
and  the  species  until  the  adult  state  has  been  reached.  Ducks  and 
drakes  are  another  familiar  instance,  but  whether  the  differences 
between  the  brilliancy  of  males  and  females  be  small  or  great,  the 
chicks  resemble  the  duller  hens. 

The  likeness  between  the  chick  and  the  duller  sex  occurs  even  in 
those  rare  and  curious  cases  in  which  the  females  are  more  brightly 
coloured  than  the  males.  Adult  cassowaries  have  a  deep  black 
plumage,  but  the  naked  skin  of  the  head,  neck  and  legs  is  often 
coloured  in  brilliant  and  fantastic  ways,  the  coloration  being  much 
more  brilliant  in  the  females,  and  in  this  case  the  young  birds 
resemble  the  males.  In  some  of  the  curious  little  button  quails,  or 
hemipodes,  the  sexes  are  alike,  but  in  most  of  them  the  females  are 
decorated  with  reddish  collars  and  other  conspicuous  patches  and 
marks,  whilst  the  males  are  more  dully  coloured.  The  chicks  in  their 
young  plumage  resemble  the  males.  The  female  painted  snipe  of 
Africa  and  Asia  has  a  brown  head  with  ruddy  marks  on  the  sides  of 
the  face  and  round  the  neck,  whilst  the  back  is  brownish-green  with 
dark  flecks  and  bright  golden-yellow  "  eye  "  markings.  The  male 
is  a  duller  bird  with  almost  no  trace  of  the  reds  and  golden-yellows 
that  light  up  his  partner.  The  young  birds  are  like  the  males.  In 
the  so-called  grey  phalarope,  a  plover-like  bird  which  occasionally 
visits  England  in  spring  and  autumn,  but  which  breeds  in  the  far 
north,  the  female  is  conspicuously  brighter  in  her  breeding  plumage. 
The  breast  and  under  parts  are  bright  chestnut  in  colour,  whilst  the 
head,  back  and  upper  part  of  the  wings  and  tail  are  glossy  black,  the 


no  CHILDHOOD  OF  ANIMALS 

individual  feathers  being  margined  with  yellow- gold  or  vivid  white. 
The  male  is  a  pale  image  of  his  mate.  In  the  eclipse  plumage  the 
sexes  are  much  alike  and  very  like  the  eclipse  plumage  of  the  allied 
red-necked  phalarope.  The  ground  colour  is  a  greyish- white,  whilst 
the  upper  parts  are  less  glossy  and  paler,  with  the  bright  margins  oi 
the  feathers  very  inconspicuous.  The.  young  birds  are  paler  than 
the  males,  and  more  closely  resemble  the  eclipse  plumage. 

The  best-known  instances  of  the  changes  to  "  eclipse  "  plumage 
are  found  in  the  ducks,  game  birds,  waders,  herons,  some  of  the 
tanagers  and  the  weaver-birds.  The  little  weaver-birds  sho\v 
almost  every  degree  of  likeness  between  the  sexes  ;  in  some  cases 
the  males  are  very  brightly  coloured  and  the  females  dull,  in  others 
the  colouring  of  the  two  is  nearly  alike.  They  pass  into  a  dull 
eclipse  and  remain  in  that  condition  for  nearly  six  months,  and  then 
assume  the  breeding  colours  again.  The  young  birds  are  always 
more  like  the  hens  and  the  eclipse  stages,  the  brilliant  blacks, 
scarlets  and  purples  being  absent  and  replaced  by  mottled  brown. 

When  both  sexes  are  alike,  the  young  in  their  first  true  plumage 
are  usually  unlike  the  adults  and  are  much  duller  and  browner. 
Examples  of  this  occur  in  almost  every  group  of  birds.  Sometimes 
the  change  from  immature  to  adult  plumage  occurs  at  a  single  moult ; 
sometimes  gradually  over  two  or  three  years  as  in  the  gulls  (see 
Plate  VIII,  p.  162),  the  feathers  changing  by  almost  imperceptible 
stages ;  sometimes,  as  in  birds-of-prey,  it  takes  a  number  of  years, 
mottled  and  striped  plumages  being  replaced  by  feathers  with  trans- 
verse bars,  then  by  self-coloured  feathers,  and  the  general  shade  oi 
the  whole  plumage  getting  darker.  In  the  king  penguin  the  brownish 
down  is  replaced  by  the  first  immature  plumage,  when  the  birds  are 
nearly  a  year  old.  The  crown  of  the  head  has  a  pale  grey  centre,  the 
neck  patch  is  light  lemon- yellow  instead  of  the  bright  golden- yellow 
of  the  adult,  and  there  is  less  distinction  between  the  back  and  the 
ventral  surface,  the  general  coloration  being  a  pale  brownish- grey, 
lighter  on  the  under  surface  and  darker  on  the  back.  Many  sea- 
birds  are  vividly  patterned  when  adult,  the  under  side  being  usually 
quite  white,  the  upper  surface  black,  or  a  shade  of  pearly- grey  with 
black  markings,  or  the  whole  bird,  as  in  the  case  of  the  gannet,  may 
be  white  except  for  the  black  tips  of  the  wings.  The  young  in  their 
first  plumage  are  nearly  uniformly  covered  with  shades  of  mottled 
brown.  So  also  ibises  and  storks,  which  when  adult  are  white,  or 
brilliantly  marked  out  with  white,  brown  and  black,  wear  a  juvenile 
garb  of  mottled  and  spotted  brown.  The  down  of  young  pelicans  is 


COLOURS  AND  PATTERNS  OF  BIRDS        in 

replaced  by  a  uniform  of  brown  before  the  brilliant  livery  of  the 
adult  is  assumed.  The  American  scarlet  flamingo  when  adult  is 
clad  in  scarlet  and  pink  ;  the  European  white  flamingo  is  white 
with  scarlet  on  the  under  surface  of  its  wings.  Young  flamingoes  about 
two  months  old,  with  their  beaks  still  nearly  straight,  have  shed  the 
nestling  down,  but  replaced  it  by  a  plumage  which  is  almost  uni- 
formly grey,  with  the  faintest  traces  of  scarlet  on  the  wings.  In 
birds-of-prey,  adult  males  and  females  are  so  alike  that  it  is  most 
difficult  to  distinguish  them,  although  the  females  are  usually 
larger.  The  young,  after  moulting  off  their  down,  assume  a  set  of 
successive  liveries  in  which  there  is  a  slow  change  from  dirty  white, 
and  mottled  and  spotted  brown,  to  the  brilliant  blacks  and  whites 
and  blue-greys  of  the  adult.  So  also  in  owls,  where  the  sexes  are 
alike,  the  young  differ  from  them,  being  usually  paler,  browner  and 
more  barred,  striped  and  mottled.  In  doves  and  pigeons,  where  the 
sexes  are  alike,  the  young  are  usually  more  mottled,  and  especially 
in  the  brightly  coloured  fruit  pigeons  are  browner  and  with  little 
trace  of  the  metallic  sheens  and  brilliancy  of  the  adults.  The 
common  cuckoo  is  almost  exactly  alike  in  tne  two  sexes  ;  the  back 
is  uniformly  ashy  grey  with  small  white  spots  on  the  darker  tail,  and 
the  under  parts  are  white  with  dusky  bars.  The  young,  in  immature 
plumage,  which  they  wear  until  they  are  as  large  as  their  parents, 
are  clove-brown  above,  and  the  feathers  of  the  wing  and  tail  are 
barred  and  mottled,  so  that  the  general  appearance  is  strikingly 
different  from  that  of  the  adult.  The  young  of  thrushes  and  fly- 
catchers are  clad  in  a  completely  spotted  plumage,  but  the  adults 
are  generally  uniformly  covered  above. 

When  the  sexes  are  alike  or  nearly  alike,  and  especially  when  they 
are  brilliantly  coloured,  the  young  in  a  few  cases  may  be  like  the 
adults.  In  kingfishers  the  young  are  only  a  little  less  brilliant  than 
the  adults.  In  orioles,  where  the  adults  are  usually  very  brilliant, 
the  young  are  only  a  little  less  brilliant.  In  parrots  almost  every 
condition  from  dull  to  brilliant  young  is  found.  In  those  such  as 
the  nestors,  where  the  coloration  is  never  very  brilliant,  and  where 
there  is  a  good  deal  of  mottled  brown  in  the  plumage,  the  young  are 
conspicuously  browner  and  more  mottled.  In  other  parrots,  the 
first  true  feathers  may  be  as  bright  as  those  of  the  adult.  In 
the  Eclectus  parrots,  where  both  males  and  females  are  brilliant, 
but  the  males  are  green  and  the  females  red,  this  distinction 
between  the  sexes  is  carried  backwards,  so  that  a  young  male,  still 
clad  in  purplish  down,  shows  the  brilliant  green  wings  of  the  adult. 


H2  CHILDHOOD  OF  ANIMALS 

Although  the  instances  I  have  given  are  the  merest  samples 
of  the  fertile  diversity  of  colour  and  pattern  displayed  by  birds, 
they  show  the  chief  types  of  relation  between  the  characters 
of  males,  females  and  young.  It  is  possible  to  build  up  from  them 
a  general  picture  of  a  process  that  appears  to  have  been  going  on. 
The  older  or  ancestral  types  of  birds  displayed  a  plumage  generally 
brownish  in  colour  with  little  difference  all  over  the  body,  and  with 
patterns  of  spots  and  stripes  and  mottlings.  At  first  the  colora- 
tion of  the  young  and  of  the  adults  in  both  sexes  was  more  or  less 
alike.  Next,  during  the  breeding  season,  the  males  began  to  assume 
brighter  colours,  and  when  the  breeding  season  was  over  relapsed 
again  into  the  dull  coloration  of  their  ancestors.  In  such  a  stage, 
the  males  in  eclipse,  the  females  and  the  young  were  all  much  alike, 
and  traces  of  this  condition  survive  in  many  existing  groups.  Next, 
the  bright  breeding  plumage  was  partly  assumed  by  the  females  as 
well  as  the  males,  but  after  the  breeding  time  was  over,  both  relapsed 
to  the  ancestral  eclipse  condition.  In  this  stage,  the  males  and 
females  in  eclipse  and  the  young  were  like  the  ancestors.  This 
stage  too  is  retained  by  many  birds,  and  the  curious  cases  where  the 
females  have  shot  ahead  of  the  males  is  only  another  variation  of 
it.  Next,  the  breeding  plumage  was  retained  for  a  longer  and 
longer  period,  for  half  the  year  as  in  the  weaver-birds,  for  all  but  a  few 
weeks  as  in  game  birds  and  most  of  the  ducks,  or  for  the  whole  year 
as  apparently  in  the  South  American  tropical  ducks,  in  kingfishers 
and  in  parrots.  There  are  traces  of  its  gradual  suppression  ;  in 
some  of  the  game  birds  and  in  some  of  the  tanagers,  for  instance,  the 
eclipse  is  represented  by  only  a  few  feathers.  When  the  eclipse  has 
been  suppressed,  it  is  only  the  young  birds  that  retain  the  dull 
ancestral  plumage,  and  there  is  every  stage  of  the  suppression  even 
of  that  in  the  young. 

And  so  the  general  trend  amongst  birds  and  mammals  alike  has 
been  from  dull  colours  and  mechanical  patterns  to  brilliant  and 
fantastic  garbs.  The  obscure  dusky  browns  and  greys  may  be  com- 
pared with  the  coal-tar  residues  from  which  chemists  have  separated 
and  distilled  a  series  of  vivid  aniline  dyes.  In  a  sense,  all  the 
shining  colours  of  the  rainbow  lie  concealed  and  confused  in  the 
turbid  mother-liquid,  and  it  is  only  by  separation  and  recombina- 
tion that  the  individual  colours  are  obtained.  And  so  in  a  sense, 
perhaps  rather  an  exact  sense,  the  obscure  hues  of  primitive  animals 
are  accidental  residues  or  waste  products  of  the  living  chemistry  of 
the  body,  and  it  is  only  when  they  have  been  split  up  and  separated 


COLOURS  AND  PATTERNS  OF  BIRDS        113 

that  they  appear  as  brilliant  patches  of  distinct  colours.  And  thus  the 
hues  that  depend  on  structure,  the  metallic  sheens  and  the  irides- 
cences and  blooms  point  to  a  greater  delicacy  of  texture,  a  refine- 
ment of  minute  structure,  a  replacement  of  the  casual  effects  of 
growth  by  more  finely  tempered  products.  In  pattern,  the  primitive 
spots  and  mottlings  may  be  and  probably  are  no  more  than  an 
accidental  result  of  the  composite  nature  of  the  skin,  and  of  the 
changes  in  the  rate  of  growth,  as  the  physiological  activities  of 
the  body  rise  and  fall.  These  are  replaced  by  patterns  of  a  less 
accidental  character.  Spots  grow  into  stripes,  or  spread  into  patches  ; 
some  areas  expand,  others  are  suppressed.  Flaps  and  outgrowths 
of  skin,  ridges  and  patches  of  hair,  tufts  and  mantles  of  feathers 
expand  and  lie  over  their  neighbouring  areas,  producing  arrangements 
that  do  not  conform  with  the  primitive  contours  and  uniform 
characters  of  the  body. 

The  set  of  changes  has  been  attended  and  made  possible  by  an 
increase  in  the  vigour  of  the  body  and  a  heightening  of  the  vital 
activities,  so  that  respiration,  excretion  and  all  the  chemical  changes 
in  the  living  laboratory  have  become  more  exuberant.  The  changes 
are  an  expression  of  surplus  vital  activity,  for  if  animals  are  to  succeed 
they  must  on  the  average  be  a  little^  more  vigorous  than  is  absolutely 
necessary  to  attain  their  purposes.  Now  and  again  a  successful 
runner  may  faint  at  the  goal,  but  in  most  cases  he  can  run  a  little 
beyond  it.  In  the  affairs  of  animals,  as  of  men,  some  reserve  is 
requisite.  And  so  it  is  natural  to  find  the  beginnings  of  more 
brilliant  colour  and  more  vivid  pattern  associated  with  the  breeding 
season,  for  in  the  breeding  season  the  strength  and  vigour  of  animal 
life  are  most  acute.  It  might  be  argued,  as  not  a  few  naturalists 
have  urged,  that  the  cumulative  beauty  of  animals  is  in  itself  acci- 
dental and  inevitable,  the  mere  result  of  their  increasing  strength  and 
vitality,  and  that  there  is  no  need  to  try  to  account  for  it  by  theories 
of  natural  selection. 

Darwin  was  always  careful  to  insist  that  natural  and  sexual 
selection  were  not  the  actual  causes  of  the  wonderful  patterns  and 
colours  that  are  displayed  in  the  animal  kingdom.  They  were  out- 
crops of  the  constitution  of  the  body,  by-products  of  its  activities, 
and  what  happened  was  that  when  a  colour  or  pattern  that  was  useful 
appeared,  it  was  favoured  in  the  struggle  for  existence,  or  in  the  eyes 
of  choosing  mates,  whilst  colours  and  patterns  that  were  harmful  or 
that  were  displeasing  were  slowly  eliminated.  I  do  not  think  it  can 
be  doubted  that  in  many  cases  the  spottings  and  mottlings  and  dull 

C.A.  H 


ii4  CHILDHOOD  OF  ANIMALS 

colours  of  young  birds  and  mammals  make  them  less  conspicuous, 
and  that  it  may  be  for  this  reason  that  they  have  been  retained  in  so 
many  animals,  in  females  that  have  to  lie  hidden  during  the  breeding 
season,  and  occasionally  in  adults.  They  have  not  been  created  for 
the  purpose  of  concealment,  but  they  have  been  retained  because  they 
existed  and  were  useful.  So  also  the  obliterating  effects  of  counter- 
shading,  the  replacement  of  primitive  patterns  by  ruptive  patterns, 
and  of  dull  colours  by  brilliant  hues,  may  have  come  about  in  the 
natural  course  of  physiological  events  and  been  retained  where  they 
were  useful  or  harmless. 


CHAPTER  VIII 
LIMITATION  OF  FAMILIES 

ELEPHANTS  may  live  until  they  are  at  least  a  century  old,  and  do 
not  begin  to  breed  until  they  are  well  over  twenty  years  of  age. 
They  are  probably  the  slowest  breeders  of  all  animals,  and  a  pair 
living  to  their  full  range  of  life  under  the  most  favourable  conditions 
would  not  bring  into  the  world  more  than  six  young  ones.  None 
the  less,  as  Darwin  calculated,  if  we  could  suppose  that  all  the 
descendants  of  a  single  pair  of  elephants  were  to  live  to  their  full 
time  of  life,  and  to  produce  their  six  offspring,  then  at  the  end  of 
the  fifth  century  the  single  pair  of  elephants  would  be  represented 
by  over  fifteen  millions  of  living  descendants.  At  the  other  end 
of  the  scale  we  may  place  a  fish  like  the  turbo t,  which  can  produce 
as  many  as  fifteen  million  eggs  in  a  season.  I  do  not  know  how 
long  it  will  live,  if  it  escape  being  caught,  but  certainly  it  is  capable 
of  living  a  good  many  years.  If  all  the  descendants  of  a  single 
pair  of  turbot  were  to  survive,  even  the  enormous  area  of  the 
oceans  would  soon  be  filled  with  a  solid  mass  of  fish.  A  pair  of 
London  sparrows  are  able  to  rear  three  or  four  clutches  of  eggs  in 
the  course  of  a  year,  and  each  clutch  contains  from  five  to  six  eggs. 
The  prolificness  of  animal  life  is  enormous.  Whether  animals  live 
a  short  time  or  a  long  time,  whether  they  produce  many  or  few 
young  in  a  season,  a  sum  in  arithmetic  shows  that  the  air,  and  the 
surface  of  the  earth,  and  the  waters  could  soon  be  filled  with  the 
incredible  swarms  of  progeny. 

And  yet  we  know  that  on  the  whole  the  relative  numbers  of 
different  species  of  animals  remain  stationary.  Now  and  again 
there  is  a  grasshopper  year,  or  a  vole  year,  or  a  wasp  year,  when 
the  destructive  forces  seem  to  have  been  swamped  by  natural 
increase.  Some  species  of  animals,  such  as  man  himself,  are  steadily 
gaining  ground  ;  others,  like  the  bison  in  America  or  the  antelopes 
and  zebras  in  South  Africa,  are  disappearing  ;  but  on  the  whole 
the  balance  of  life  is  preserved  and,  with  occasional  fluctuations, 
species  neither  gain  nor  lose  very  much  in  numbers. 


n6  CHILDHOOD  OF  ANIMALS 

It  follows  of  course  that  the  natural  rate  of  mortality  must  be 
very  high.  If  each  pair  of  sparrows  tend  to  be  turned  into  about 
twenty  sparrows  by  the  end  of  the  year,  and  yet  the  total  sparrow 
population  does  not  increase,  eighteen  out  of  twenty  must  die 
every  year — that  is  to  say,  the  sparrow  death-rate  must  be  about 
ninety  per  cent.,  the  normal  human  death-rate  in  London  being 
only  about  one  and  a  half  per  cent,  per  annum.  The  death-rate 
amongst  elephants  must  be  smaller  ;  that  amorgst  turbot  higher. 
Anyhow,  it  is  plain  that  death  takes  a  heavy  toll  of  all  living  things. 

Death  falls  most  heavily  on  young  animals.  Physically  they  are 
more  feeble  and  more  readily  succumb  to  extremes  of  heat  or 
cold,  to  starvation  or  over-eating,  to  drought  or  rain,  and  to  disease 
of  all  kinds.  But  their  plain  destiny  is  to  be  eaten.  Young  animals 
are  more  tender  and  succulent  than  old  ones.  Their  fur,  feathers, 
scales,  bones  and  other  hard  parts  offer  less  resistance  to  the  teeth 
or  claws  and  other  biting  and  grasping  organs,  and  offend  the 
stomachs  of  their  captors  less  than  those  of  full-grown  animals. 
They  are  not  only  a  more  attractive  but  an  easier  prey.  They 
cannot  fight  or  struggle  much,  they  have  feebler  powers  of  escape, 
and  less  cunning  and  resource  in  avoiding  their  enemies.  They 
form  a  great  part  of  the  food-supply  of  the  world. 

The  ultimate  source  of  the  food  of  all  animals  is  green  vegetation. 
A  vast  expanse  of  verdure,  trees,  shrubs,  grasses,  ferns  and  moss 
covers  almost  the  entire  surface  of  the  land  from  the  tops  of  the 
mountains  down  to  the  edges  of  the  sea.  All  this  green  vegetation 
is  actively  building  organic  food-material  from  the  inorganic 
elements  of  the  air  and  the  soil.  And  so  on  the  land  vegetarian 
animals  are  more  prolific  and  abundant  than  carnivorous  creatures. 
Plant-eaters  like  sheep  and  cattle,  deer  and  antelopes,  rabbits  and 
kangaroos  are  found  in  huge  numbers  and  multiply  at  incredible 
rates.  So  also  seed-  and  fruit-eating  birds  are  more  numerous 
than  carnivorous  birds  ;  grasshoppers,  locusts  and  vegetarian 
beetles  than  their  carnivorous  allies.  But  all  these  are  preyed  upon 
by  carnivorous  mammals,  birds,  reptiles  and  insects.  In  the  sea, 
on  the  other  hand,  most  of  the  animals  are  carnivorous.  The 
birds  that  live  on  the  ocean,  terns,  gulls,  petrels,  cormorants, 
are  very  numerous  indeed,  and  the  clouds  of  sea-birds  in  their 
"breeding-places  recall  the  dense  vegetarian  population  of  the  land. 
These  sea-birds  are  all  carnivorous  ;  most  of  them  are  fishers,  and 
others,  like  the  petrels,  scoop  up  the  small  Crustacea  from  the 
surface  of  the  waves.  Seals  pursue  fishes  ;  polar  bears  live  on 


LIMITATION  OF  FAMILIES  117 

seals ;  sea-elephants  and  walruses  live  on  shell-fish ;  whales, 
dolphins  and  porpoises  all  live  on  sea-animals,  and  many  of  them 
are  fierce  beasts  of  prey.  Most  fishes  are  carnivorous,  and  one 
has  only  to  think  of  the  shoals  of  herring  and  mackerel,  the  wall- 
like  masses  of  codfish  and  the  great  hauls  of  sardines  to  realise  the 
enormous  animal-eating  population  of  the  sea.  Most  of  the  lower 
forms  of  life  are  carnivorous.  The  gardens  of  the  tropic  island 
sea-bottoms,  with  their  brilliantly  coloured,  flower-like  polyps,  are 
composed  of  animals  that  live  on  other  animals  almost  exclusively. 

A  small  portion  of  the  ultimate  food-supply  of  the  sea  consists 
of  the  flotsam  and  jetsam  from  the  land,  of  waste  matter  washed 
down  by  the  great  rivers.  But  the  main  source  is  to  be  found 
in  the  sea- water  itself.  If  the  open  sea  seems  at  first  a  barren  waste, 
the  tow-net  shows  that  it  contains  myriads  of  small  animals. 
These  are  the  larvae  of  innumerable  creatures  that  live  on  the  shore 
or  on  the  bottom,  together  with  countless  wanderers  that  have  no 
fixed  abode,  but  drift  all  their  lives  with  the  ocean  currents. 
Amongst  them  are  great  numbers  of  small  plants,  like  the 
protococci  that  form  the  green  scum  on  pools  of  rain-water,  or  the 
diatoms  familiar  to  every  one  who  uses  a  microscope.  These,  in 
the  fashion  of  terrestrial  green  plants,  build  up  food-material  from 
the  inorganic  salts  in  the  sea  and  from  the  gases  of  the  air.  Little 
animals  live  on  them  and  are  in  turn  fed  on  by  larger  animals.  In 
the  depths  of  the  ocean,  where  no  light  penetrates,  green  plants 
cannot  live,  and  the  food-supply  must  be  derived  from  live  or  dead 
animals  that  rain  down  from  the  surface. 

And  so  on  land  and  in  the  sea,  in  the  air  and  in  the  waters,  living 
creatures  are  ceaselessly  devouring  other  living  creatures,  and  the 
feeble  and  succulent  young  are  the  readiest  victims.  The  more 
powerful  carnivorous  animals  seem  to  rejoice  in  their  strength 
and  skill,  and  many  of  them  destroy  far  more  victims  than  they 
require  for  food.  Others  are  extremely  voracious,  and  appear  to 
have  no  limit  to  their  capacity  for  digestion  or  to  their  appetite. 
If  we  reflect  on  the  dangers  from  accident,  disease  and  the  host  of 
hungry  enemies,  the  wonder  seems  to  be,  not  that  species  occasionally 
have  become  extinct,  but  that  any  have  maintained  their  existence. 

The  most  common  device  in  the  animal  kingdom  to  meet  the 
immense  destruction  of  life  is  for  the  young  to  be  produced  in 
enormous  quantities.  In  the  sea  especially,  where  most  animals 
are  carnivorous,  the  ripe  females  are  bloated  with  a  great  burden 
of  eggs,  to  be  counted  by  millions  or  thousands  or  hundreds,  and 


n8  CHILDHOOD  OF  ANIMALS 

large  tracts  of  water  become  changed  in  colour  because  they  swarm 
with  innumerable  multitudes  of  tiny  embryos.  Sea-anemones 
and  jelly-fish,  starfish  and  sea-urchins,  the  various  tribes  of  worms, 
crustaceans  and  molluscs,  sea-squirts  and  fishes  turn  adrift  a  huge 
and  uncared-for  progeny  out  of  which  a  few  lucky  individuals 
reach  maturity.  We  know  the  vast  broods  that  many  insects 
produce,  we  have  seen  a  nettle  black  with  the  caterpillars  of  a 
single  butterfly,  or  a  carcass  pullulating  with  the  maggots  of 
one  blow-fly.  Although  amongst  the  higher  animals  we  count 
large  families  by  sixes  and  tens,  instead  of  by  hundreds  and  thousands 
or  millions,  we  know  the  amazing  fertility  of  many  small  mammals 
and  birds. 

To  produce  a  large  family,  making  little  provision  for  it,  is  a 
wasteful  and  improvident  method  of  maintaining  the  species.  To 
limit  the  number  of  the  young,  to  lavish  on  them  parental  care  and 
not  to  throw  them  on  their  own  resources  until  they  are  well  fitted 
to  make  a  brave  fight  against  the  troubles  of  the  world,  are  surer 
means  of  maintaining  the  numbers  of  the  species  and  enabling  it 
to  reach  a  higher  level  of  efficiency.  Devices  of  this  kind  have  been 
adopted  in  almost  every  group  of  the  animal  kingdom,  but  become 
more  universal  and  more  complete  as  the  scale  of  life  is  ascended. 
Not  only  are  the  numbers  in  the  family  reduced,  but  the  period  of 
youth  becomes  longer.  The  protected  young  are  no  longer  at 
once  absorbed  by  the  immediate  problems  of  life,  by  the  struggle 
for  mere  existence.  They  form  in  each  division  of  the  animal 
kingdom  a  kind  of  aristocracy  with  leisure  for  education  and  training, 
and  with  the -opportunity  of  modifying  instinct  by  practice.  The 
word  family  in  their  case  acquires  a  new  and  real  meaning.  It  no 
longer  is  a  name  simply  for  the  offspring  of  a  single  pair  of  parents, 
but  comes  to  imply  an  association  of  brothers  and  sisters,  of  young 
and  parents  living  together  in  a  new  relation,  not  merely  temporarily 
united  by  the  attraction  of  sex,  but  forced  to  live  together  in  some 
kind  of  harmony,  with  some  degree  of  mutual  toleration.  The 
appearance  of  the  family  provides  opportunity  for  developing  the 
social  habits  which  are  the  foundation  of  the  higher  sides  of 
mental  and  emotional  life.  Co-operation,  friendship  and  love 
which  is  not  sexual  attraction  find  their  first  beginnings  in  limitation 
of  the  numbers  of  the  young  and  in  the  association  of  young  and 
old  in  the  family  tie. 

In  the  lower  animals  the  limitation  of  the  numbers  of  the  young 
and  the  institution  of  parental  care  are  often  associated  with 


LIMITATION  OF  FAMILIES 


119 


•\ 


specially  hard  conditions,  and  are  found  amongst  creatures  that  live 
in  very  cold  water,  as  in  the  polar  regions,  or  in  fresh  water,  where 
the  strong  currents  and  rapid  changes  of  temperature  are  hostile 
to  the  feeble  young,  or  in  the  strenuous  and,  storm-tossed  life  of  the 
shore.  It  may  well  be  that  of  the  multitude  of  young  produced, 
only  those  that  accidentally  remained  with  their  parents  survived, 
and  that  afterwards  the  total  number  was  gradually  reduced  and 
the  arrangements  for  retaining  the  young  with  their  parents  made 
more  perfect.  In  most  of  the  sea-urchins  enormous  numbers  of 
eggs  are  discharged  every  season  ;  the  number  in  the  common  edible 
form  sold  in  the  markets  of  the 
south  of  France  and  Italy  has 
been  calculated  at  twenty  millions. 
These  eggs  are  fertilised  in  the 
sea  and  the  young  embryos  drift 
without  any  help  or  protection 
from  their  parents.  In  some  of 
the  urchins  from  the  Antarctic 
seas,  Sir  Wyville  Thomson  found 
that  there  were  little  shallow 
pouches  on  the  outside  of  the 
shell  or  test  of  the  female,  and 
that  the  spines  bordering  these 
were  long  and  curved  over  to 
form  basket-work  lids.  The  eggs, 
comparatively  few  in  number,  were  passed  into  these  pouches  and 
there  developed  directly  into  small  urchins,  which  thus  enjoyed 
the  security  and  protection  given  by  the  mother  until  they  had 
reached  a  considerable  size  (Fig.  26).  So  also  the  most  common 
sea-cucumbers  produce  eggs  in  enormous  numbers,  and  these 
develop  into  unprotected  embryos  in  the  water.  In  a  sea- 
cucumber  from  the  Falkland  Islands  the  two  rows  of  tube-feet 
(the  bivium)  along  the  dorsal  surface  are  rudimentary,  and  not 
used  for  locomotion  in  the  females  ;  along  these  a  dozen  or  so 
of  little  animals  are  attached,  looking  like  a  row  of  yellow  plums, 
and  remain  there  until  they  are  nearly  fully  grown  and  able 
to  live  the  independent  lives  of  the  adult.  Although  in  most 
starfish  and  brittle-stars  large  numbers  of  young  have  to  encounter 
the  huge  mortality  of  a  free  life  in  the  waters,  in  others  only  a  few 
are  produced,  and  creep  about  on  the  body  of  the  mother  (Fig.  27) 
or  develop  in  a  brood-pouch  formed  on  the  outer  surface  of  her  body. 


FIG.  26.     A  Sea-urchin  carrying  its 
young.  (After  WYVILLE  THOMSON.  ) 


I2O 


CHILDHOOD  OF  ANIMALS 


In  most  of  the  marine  worms  very  many  eggs  are  laid,  and 
these  develop  into  free-swimming  larvae,  subject  to  the  usual 
destruction  by  innumerable  foes.  In  a  few  the  number  is  re- 
duced and  the  young  are  carried  attached  to  the  body  of  the 
mother,  sometimes  contained  in  a  pair  of  brood-pouches  on  the 
under  surface  of  her  body.  In  terrestrial  and  fresh- water  worms, 
such  as  the  common  earthworm,  the  number  of  young  is  reduced, 
and  these  are  enclosed  in  little  protective  cases  or  cocoons  formed 
by  the  parent  and  suspended  to  water- weeds,  or  hung  up  against 

the  wall  of  the  burrow. 
Leeches  arrange  for 
their  young  in  a  similar 
fashion,  but  there  are 
some  in  which  the  eggs 
remain  attached  to  the 
body  of  the  mother, 
to  the  under  surface  of 
which  the  young  leeches 
fix  themselves  when 
they  are  hatched,  by 
their  suckers,  and  so 
secure  protection. 

All  the  crustaceans 
have  gone  a  consider- 
able way  in  the  reduc- 
tion of  the  number  of 
eggs  produced  and  all  of  them  display  at  least  the  beginnings  of 
parental  care.  In  a  very  few,  including  some  of  the  fish-lice, 
the  eggs  are  attached  by  the  mother  to  water- weeds  or  stones. 
In  most  they  are  carried  about  by  the  female  in  a  brood-pouch, 
or  attached  to  the  legs  or  to  a  special  chamber  formed  from 
the  flap  that  protects  the  external  gills.  When  the  eggs  hatch,  in 
most  cases  free-swimming  larvae  emerge,  and  these  without  further 
aid  from  the  parents  are  transformed  to  the  adults  by  a  series  of 
moults.  During  their  larval  life,  however,  prodigious  numbers  are 
destroyed,  for  crustacean  larvae  form  a  most  important  part  of  the 
food-supply  of  fishes  and  aquatic  birds,  and  the  different  groups 
supply  many  cases  of  a  still  greater  protection  of  the  young  by  the 
parents,  with  reduction  in  the  number  produced  and  a  much  higher 
percentage  of  success  in  reaching  adult  life.  The  summer  eggs  of 
the  little  water-fleas  (Cladocera)  are  hatched  in  a  brood-pouch 


FIG.  27.     A  Brittle-star  carrying  its  young. 
(After  WYVIJLLE  THOMSON.) 


LIMITATION  OF  FAMILIES  i2r 

under  the  shell  on  the  back,  and  in  some  cases  are  fed  by  a  nutritive 
juice  which  reaches  them  from  a  large  blood-space.  In  many  others > 
the  eggs  are  carried  in  pouches  attached  to  the  body  of  the  parent, 
or  are  suspended  to  her  legs.  In  all  these  small  flea-like  crustaceans, 
however,  the  development  is  indirect,  and  at  least  some  meta- 
morphoses are  gone  through.  In  the  sandhoppers  and  slaters  the 
numbers  of  the  young  are  still  further  reduced,  and  the  embryos, 
carried  by  the  mothers  in  brood-pouches,  are  fed  and  protected 
until  they  have  almost  completely  attained  the  adult  structure. 
In  the  higher  crustaceans,  such  as  shrimps  and  prawns,  crabs, 
lobsters  and  crayfishes,  the  eggs  are  rather  numerous,  and  are 
cemented  to  the  under  surface  of  the  body  of  the  mother,  forming 
the  familiar  •"  berries  "  which  in  prawns,  crabs  and  lobsters  turn 
red  on  boiling.  In  those  that  live  in  the  sea,  when  the  eggs  hatch , 
the  larvae  leave  the  mother  and  have  to  fend  for  themselves.  In 
the  fresh-water  forms,  however,  such  as  the  familiar  crayfish,  the 
eggs  are  much  larger  in  proportion  to  the  size  of  the  animals,  and 
are  much  less  numerous.  The  complete  development  takes  place 
before  hatching,  whilst  the  egg  is  still  carried  by  the  mother,  and 
when  the  young  creature  emerges  it  is  almost  a  perfect  miniature 
of  the  parent.  It  enjoys  the  protection  of  the  mother  for  a  still 
longer  period,  clinging  to  her  with  its  pincers. 

Scorpions  and  spiders  are  terrestrial,  air-breathing  creatures  of 
high  organisation,  and  show  many  instances  of  elaborate  precautions 
for  the  care  of  the  young,  and  of  a  resulting  reduction  in  the  numbers 
of  the  brood.  Scorpions  are  the  larger,  more  powerful  and  better 
armed,  and  in  them  the  process  has  gone  furthest.  The  eggs  are 
hatched  inside  the  body  of  the  mother,  and  each  brood  consists  of 
no  more  than  about  a  dozen  individuals,  which  are  born  two  at  a 
time.  From  their  first  appearance  they  can  be  recognised  as  little 
scorpions,  differing  only  in  size,  in  paler  colour  and  in  a  few  minor 
details  from  their  parents.  They  at  once  find  their  way  to  the  back 
of  the  mother,  and  the  whole  family  is  carried  in  this  way  for  some 
weeks,  until  the  young  creatures  have  gone  through  several  moults 
and  become  large  enough  and  strong  enough  to  look  after  themselves. 
During  this  time  they  enjoy  protection,  for  a  scorpion  is  a  formidable 
creature  with  few  enemies  sufficiently  daring  to  attack  it.  The 
young  feed  on  scraps  of  the  spiders,  cockroaches  and  other  insects 
which  the  mother  catches  and  slowly  picks  to  pieces. 

Spiders  are  far  from  having  reached  the  economy  of  breeding 
habits  shown  by  scorpions.  The  young  are  always  hatched  outside 


122  CHILDHOOD  OF  ANIMALS 

the  body  of  the  mother,  and  although  they  are  plainly  spiders 
at  their  first  appearance,  they  go  through  a  number  of  moults 
before  they  are  capable  of  independent  life.  They  are  fragile  and 
delicate  little  creatures  and  suffer  great  destruction  from  storms  of 
wind  and  rain,  from  drought  and  floods,  and  although  the  numbers 
produced  at  a  brood  are  very  much  reduced  from  the  enormous 
quantities  found  among  marine  animals,  they  are  often  large.  In 
some  of  the  spiders  belonging  to  the  same  group  as  the  garden  spider, 
which  spins  its  huge  geometrical  snares  in  autumn,  as  many  as  from 
six  hundred  to  two  thousand  eggs  may  be  laid  by  a  single  female. 
The  numbers  are  proportioned  to  the  special  difficulties  to  be  met, 
and  in  some  of  the  spiders  that  live  in  the  safe  retreat  afforded  by 
dark  caves  there  may  be  no  more  than  four  or  five  eggs. 

Maternal  care  begins  before  the  eggs  are  laid.  Most  female 
spiders  spin  a  little  web  of  silk,  deposit  the  eggs  on  this  and  then 
cover  them  up  with  another  layer.  The  egg-bags,  or  cocoons, 
are  often  distinctively  shaped  and  coloured.  Those  of  the  large 
garden  spider  are  globular,  bright  yellow  in  colour  and  almost  as 
wide  across  as  a  shilling.  Sometimes  the  cocoons  are  hidden  in  a 
natural  shelter,  sometimes  suspended  to  the  under  surface  of  a 
leaf,  or  even  hung  up  in  the  neighbourhood  of  the  web,  and  the  true 
cocoons  may  have  woven  around  them  curiously  shaped  cases  of 
thick  resistant  silk,  which  further  protects  them  against  the 
weather.  The  hunting  spiders,  which  pursue  their  prey  on  foot, 
running  swiftly  over  the  ground  and  springing  on  insects  with 
great  bounds,  usually  fasten  the  globular  cocoon  by  a  firm  thread 
to  the  under  surface  of  their  body  and  let  it  bump  along  after  them. 
The  nests,  burrows  and  other  retreats  that  spiders  excavate  or 
spin  are  usually  for  their  own  protection  and  not  specially  for  the 
young.  But  the  little  English  spider  that  makes  a  tent-like 
dwelling  of  soft  fluffy  threads  and  is  found  in  almost  every  bush 
and  shrub  in  summer,  places  her  green  cocoons  in  her  own  tent, 
and  the  young  when  they  come  out  live  with  the  mother  for  some 
weeks.  The  large  twater-spider  builds  a  similar  dome  of  silk  under 
water,  carries  down  globules  of  air  entangled  in  the  hairs  of  the 
body,  and  sets  them  free  under  the  dome  until  it  becomes  an  anchored 
diving-bell,  within  which  the  eggs  are  laid  and  the  young  hatch 
and  live,  until  they  turn  out  to  make  their  own  retreats. 

When  young  spiders  hatch  they  are  pale  in  colour,  and  as 
they  are  covered  with  a  thin  membrane,  can  neither  spin  nor  eat. 
After  a  few  moults  they  differ  from  the  parents  only  in  size.  Until 


LIMITATION  OF  FAMILIES  123 

two  or  three  moults  have  been  gone  through,  and  this  usually 
occupies  about  a  week,  the  young  spiders  remain  near  the  cocoon 
or  the  mother.  Amongst  those  that  spin  geometrical  webs, 
the  young  cling  together  in  a  great  yellow  ball,  but  if  this  be 
disturbed  or  touched,  they  suddenly  scatter  into  a  golden  mist, 
each  little  spider  shooting  out  at  the  end  of  a  long,  almost  invisible 
thread  of  silk,  and  then  when  the  disturbance  is  over,  they  re- 
assemble. This  period  of  dwelling  together  in  amity  does  not 
last  long,  for  as  soon  as  the  spiders  are  able  to  feed  they  assume 
the  fierce  habits  of  their  race  and  are  ready  to  fall  on  each  other. 
At  first,  however,  they  settle  down  near  their  original  home,  each 
making  its  own  web. 

When  the  young  of  the  wolf -spiders  hatch,  they  soon  leave  the 
cocoon.  The  broods  are  much  smaller  in  numbers,  as  the  mothers 
could  not  drag  about  a  heavy  weight,  and  the  young  creatures 
climb  on  the  back  of  their  mother  and  accompany  her  on  her 
hunting  expeditions. 

Sooner  or  later,  however,  spiders  have  to  disperse  to  avoid  the 
reawakened  instincts  of  their  mother  and  the  fierce  attentions  of 
their  hungry  brothers  and  sisters.  Many  of  them  do  it  by  a  curious 
device,  making  use  of  the  wind  like  the  winged  or  tufted  seeds  of 
plants.  On  a  fair  but  windy  morning  they  climb  up  to  the  highest 
point  available,  to  the  topmost  bar  of  a  fence,  to  the  edge  of  a  high 
wall  or  to  the  extreme  twigs  of  bushes.  There  they  raise  them- 
selves on  the  ends  of  their  legs  with  the  abdomen  held  erect  and 
pointed  backwards  away  from  the  wind.  Then  little  tufts  of  delicate 
silk  are  shed  out  from  the  spinnerets  and  float  in  the  breeze  until 
they  are  long  enough  and  have  enough  surface  to  carry  the  spider 
from  its  support.  The  caprice  of  the  breeze  determines  the  course 
and  distance  of  the  flight,  but  just  as  a  spider  can  haul  in  the  thread 
which  binds  it  to  a  spot  from  which  it  has  dropped,  so  when  it  is 
floating  it  can  roll  up  its  sail,  piece  by  piece,  until  it  descends 
to  the  ground. 

Insects  in  every  stage  of  their  lives  suffer  greatly  from  the 
inclemency  of  the  weather,  the  ravages  of  disease,  and  the  attacks 
of  other  insects,  of  spiders,  and  especially  of  frogs,  reptiles,  birds 
and  mammals,  many  of  which  live  almost  entirely  on  an  insect 
diet.  Some  insects  are  extremely  prolific,  but  none  the  less,  especially 
in  the  higher  members  of  the  higher  groups,  the  old  thriftless  method 
of  large  broods  left  to  take  their  chance  in  the  world  is  replaced  by 
smaller  broods  for  the  safety  of  which  great  precautions  are  taken. 


124  CHILDHOOD  OF  ANIMALS 

It  is  a  singular  fact  that  in  by  far  the  greater  number  of  cases 
the  provision  for  the  young  is  made  by  parents  destined  never  to 
see  their  offspring,  and  who  are  nearly  always  dead  even  before 
the  eggs  have  hatched,  and  it  is  therefore  only  in  a  very  few  cases 
that  there  is  an  actual  association  between  the  hatched  young  and 
their  mothers.  The  provision  seldom  extends  to  more  than  select- 
ing or  preparing  a  suitable  place  in  which  the  eggs  may  hatch  and 
where  the  larvae  when  they  emerge  may  have  the  proper  surroundings 
and  the  proper  food. 

Among  the  orthopterous  insects  the  eggs  are  rather  numerous, 
and  are  frequently  scattered  on  the  ground  without  any  pre- 
cautions. The  common  earwig,  however,  has  been  observed  collect- 
ing her  eggs  with  her  mandibles,  arranging  them  in  heaps  and 
brooding  over  them.  When  the  young  emerge,  the  mother  takes 
no  further  interest  in  them,  and  after  a  few  moults  they  are  com- 
pletely like  the  adult.  Cockroaches  enclose  the  small  number 
of  eggs  they  produce  in  a  cocoon,  which  is  formed  in  the  interior  of 
the  body.  When  the  cocoon  leaves  the  body,  it  is  carried  about  by 
the  mother  for  some  time  and  then  hidden  in  a  chink,  or,  in  the  case 
of  the  common  cockroach,  most  frequently  just  under  the  edge  of 
a  carpet  or  sheet  of  oil-cloth.  The  praying  mantis  constructs  a 
chambered  egg-case,  which  it  attaches  to  wood  or  stones.  Leaf 
insects  and  stick  insects  deposit  very  large  numbers  of  eggs 
almost  at  random,  and  the  young  soon  after  they  are  hatched 
usually  have  the  appearance  of  their  parents,  although  some,  such 
as  the  Ceylonese  stick  insect,  go  through  remarkable  changes  of 
shape  and  colour.  Stick  insects  kept  in  a  glass  vivarium  case  in 
the  Insect  House  of  the  London  Zoological  Gardens  produced  an 
enormous  number  of  young.  These  began  to  migrate  when  they 
were  so  small  that  they  could  pass  through  the  perforated  zinc 
back  of  their  cage,  or  squeeze  between  the  door  and  its  hinge,  and 
wandered  all  over  the  Insect  House.  The  females  of  the  large 
brown  locusts  and  grasshoppers  have  several  hard  projections  at 
the  tip  of  the  body,  and  with  these  excavate  little  chambers  in  the 
ground  in  which  the  eggs  are  laid  along  with  a  fluid  exudation  that 
sets  to  form  a  resistant  lining  to  the  chamber.  The  eggs  of  these 
locusts  are  much  sought  by  other  insects,  especially  beetles,  which 
are  able  to  penetrate  the  hard  chambers.  The  young  of  the 
migratory  locust  go  through  a  number  of  colour  changes,  the 
meaning  of  which  is  unknown,  soon  after  hatching.  On  leaving  the 
egg  the  larva  at  once  moults,  and  the  new  skin  is  green  at  first,  but 


LIMITATION  OF  FAMILIES  125 

then  becomes  brown,  and  in  a  few  hours  is  black.  In  six  days 
there  is  a  second  moult,  after  which  the  young  insect  is  black,  with 
spots  and  bands  of  white,  and  coloured  streaks  along  the  posterior 
end  of  the  body.  In  about  another  week  there  is  another  moult, 
and  the  coloured  streaks  expand  to  form  rosy  patches.  In  less 
than  three  weeks  there  have  been  six  moults,  with  successive 
changes  from  pink  to  yellow  and  blue,  and  the  insect  in  its  final 
form  is  chiefly  black  with  blue  and  rosy  marks.  Female  green 
grasshoppers  have  nearly  always  a  long  ovipositor  at  the  tip  of 
the  abdomen,  and  with  this  dig  a  shelter  for  the  eggs.  Crickets 
have  a  long  ovipositor,  and  do  nothing  for  their  young  after  the 
eggs  have  been  laid  in  a  suitable  hole.  The  mole-crickets  make 
burrows  for  themselves  underground,  using  their  strong  spade-like 
front  legs  for  the  purpose,  but  the  female  also  constructs  a  special 
chamber  in  which  about  a  hundred  eggs  are  laid  and  where  there 
is  a  space  for  the  newly  hatched  young  to  lurk.  The  clear-winged 
stone-flies,  dragon-flies  and  may-flies  simply  drop  their  eggs  into 
water,  and  there  the  larvae,  as  I  have  described  in  an  earlier  chapter, 
live  a  totally  different  life  from  that  of  the  adults. 

The  termites,  or  so-called  white  ants,  which,  however,  are  related 
to  may-flies  and  dragon-flies  rather  than  to  ants,  show  one  of 
the  most  remarkable  developments  of  family  life  in  the  animal 
kingdom.  The  conditions  differ  a  good  deal  in  different  species. 
Each  colony  is  really  a  patriarchal  family,  the  descendants  of  a 
single  pair  living  with  their  parents  in  a  community  and  playing 
different  parts  in  it.  One  of  the  simplest  cases  is  that  of  a  European 
termite  the  habits  of  which  have  been  studied  in  Sicily.  A  winged 
pair  take  up  their  abode  in  a  dead  or  decaying  tree,  living  on  the 
rotting  wood  and  hollowing  out  chambers  and  burrows.  They 
reproduce  slowly,  being  surrounded  by  fifteen  or  twenty  young 
after  the  first  year,  but  more  rapidly  afterwards,  and  in  a  few  years 
the  family  may  reach  as  many  as  a  thousand.  The  eggs  that 
hatch  out  produce  larvae  which  are  at  first  true  males  and  females. 
Some  of  these  develop  slowly,  and  in  rather  more  than  a  year 
become  perfect  winged  insects,  and  leave  the  colony  in  pairs  to 
found  new  colonies  elsewhere,  after  having  spent  their  youth,  so  to 
say,  as  servants  in  their  parents'  house.  Other  individuals  develop 
more  quickly,  but  when  fully  grown  are  blind  and  wingless.  Their 
reproductive  organs  remain  in  a  condition  of  arrested  development, 
and  their  jaws  and  heads  become  of  enormous  size.  In  the  more 
highly  developed  colonies,  these  individuals,  known  as  soldiers,  are 


126  CHILDHOOD  OF  ANIMALS 

fed  differently,  and  it  appears  as  if  the  peculiar  food  they  receive 
were  the  stimulus  to  their  different  mode  of  development.  The 
use  of  the  soldiers  is  to  defend  the  colony,  by  blocking  up  apertures 
with  their  enormous  heads  and  powerful  jaws,  threatening,  attack- 
ing and  driving  away  enemies.  In  their  youth  these  warriors 
have  undergone  a  kind  of  forced  conscription,  but  they  have  been 
so  shaped  and  trained  for  their  special  functions  that  they  cannot 
resume  the  normal  life  and  normal  functions  of  perfect  individuals. 

In  some  of  the  numerous  African  species  of  termites  which 
construct  chambered  dwellings  many  feet  high,  the  colonies  are 
much  more  elaborate,  but  remain  essentially  single  families,  all 
being  the  descendants  of  one  pair,  the  king  and  queen.  These  lose 
their  wings,  and  the  queen  becomes  enormous  in  size,  and  lays 
almost  incalculable  quantities  of  eggs.  The  larvae  that  hatch  out 
are  at  first  much  alike,  but,  owing  partly  to  differences  in  food, 
some  remain  small,  blind  and  wingless,  with  arrested  sexual  organs, 
and  live  their  whole  lives  as  workers,  constructing  the  chambers, 
providing  the  food,  tending  the  king  and  queen,  soldiers  and  young. 
Others  also  remain  blind  and  wingless,  but  grow  several  times  as 
large  as  the  workers,  and  develop  enormous  heads  with  strong  jaws 
or  with  peculiar  snout-like  protrusions  from  the  forehead  ;  these 
also  remain  in  a  condition  of  arrested  sexual  development,  and  act 
as  soldiers  or  warriors,  being  useful  only  for  the  defence  of  the  colony. 
Finally,  other  larvae  develop  into  perfect  winged  insects,  male  or 
female,  and  leave  the  colony  in  great  numbers,  most  of  them 
perishing,  but  a  few  becoming  the  founders  of  new  colonies.  These 
elaborate  communities  may  consist  of  many  thousands  of  individuals, 
but  they  remain  a  single  family,  and  it  is  believed  that,  whilst 
occasionally  a  new  king  and  queen  may  be  reared,  in  most  cases 
the  community  perishes  when  the  original  founders  die. 

The  saw-flies,  like  most  insects,  do  little  more  for  their  young 
than  deposit  the  eggs  in  suitable  places.  The  females  are  pro- 
vided with  a  pair  of  sharp,  toothed  blades,  placed  on  the  lower  side 
of  the  abdomen,  by  which  they  saw  into  the  tissues  of  plants  and 
prepare  a  place  in  which  the  eggs  may  be  laid  and  the  newly  hatched 
larvae  find  food.  In  one  rare  case,  however,  maternal  care  goes 
further.  The  female  deposits  her  eggs,  about  eighty  in  number 
(and  this  is  much  less  than  the  usual  number  in  these  prolific 
insects)  on  the  leaf  of  a  eucalyptus,  then  watches  over  them  until 
they  hatch,  and  remains  for  some  time  with  the  young  larvae, 
standing  over  them  with  outstretched  legs,  and  so  warding  off 


LIMITATION  OF  FAMILIES  127 

enemies.  The  gall-flies  are  provided  with  a  delicate  ovipositor ,. 
and  by  means  of  this  the  females  pierce  the  tissues  of  plants  to 
deposit  their  eggs.  Some  of  them,  however,  use  their  weapons  to- 
insert  their  own  eggs  into  the  actual  eggs,  or  more  often  the  soft  larvae, 
of  other  insects,  and  the  young  when  they  hatch  are  thus  provided 
with  a  living  prey.  The  ichneumon-flies  have  similar  habits. 
They  prey  chiefly  on  the  caterpillars  of  butterflies  and  moths,  and 
when  they  have  found  a  suitable  victim,  which  may  be  many 
hundred  times  larger  than  themselves,  swoop  on  its  back,  pierce 
the  body  with  the  ovipositor  and  leave  their  eggs  in  it.  The  larvae 
thus  hatch  out  in  a  favourable  and  protected  position  and  eventually 
devour  their  unwilling  host.  In  many  cases  their  ravages  are  so- 
timed  that  the  caterpillar  is  not  killed  before  it  has  pupated,  and 
its  parasites  then  go  through  their  own  pupation  within  the  chrysalid. 
Those  who  breed  butterflies  and  moths  have  to  take  sedulous 
precautions  to  keep  off  ichneumon-flies  from  the  eggs  and  cater- 
pillars they  are  rearing,  and  none  the  less  often  find  that  at  the 
time  when  the  butterfly  should  appear  there  comes  out  only  a 
swarm  of  little  flies. 

The  females  of  the  gaudy  little  ruby-flies  haunt  places  occupied 
by  solitary  wasps.  When  one  has  discovered  a  cell  with  a  young^ 
wasp  larva  in  it,  together  with  the  store  of  caterpillars  that 
the  wasp  has  placed  for  the  benefit  of  its  own  grub,  she  places 
a  few  of  her  eggs  in  it,  and  the  larva  devours  not  only  the 
wasp-grub  but  the  caterpillars  stored  for  the  latter.  These 
ruby-flies  which  have  thus  learned  to  provide  so  well  for  their 
young  lay  very  few  eggs,  and  of  those  that  are  laid  usually  only  one 
hatches  out. 

The  larvae  of  bees  are  soft,  legless  grubs,  and  are  placed  in  cells 
constructed  by  the  mothers  themselves  in  the  case  of  the  solitary 
bees,  or  by  the  arrested  females  known  as  workers  in  the  social 
bees,  whilst  in  some  parasitic  bees  the  mothers  deposit  the  eggs  in 
cells  constructed  by  other  bees,  and  the  parasitic  grubs  hatch  out 
more  quickly  and  devour  the  food  prepared  for  their  host.  In  the 
solitary  bees  each  cell  is  packed  with  a  mixture  of  honey  and  pollen 
collected  by  the  mother  ;  in  the  social  bees  the  food  is  collected  by 
the  workers,  who  feed  and  tend  the  young. 

The  female  solitary  wasps  construct  a  cell  for  each  egg,  in  which 
they  store  from  eight  to  a  dozen  caterpillars,  which  are  paralysed 
by  the  sting  and  so  remain  fresh  and  alive  until  the  wasp-grub  is 
ready  to  devour  them.  Among  the  social  wasps,  each  colony  or 


128  CHILDHOOD  OF  ANIMALS 

nest  is  really  a  family  founded  by  a  single  female  which  has 
hibernated.  In  spring  she  selects  a  suitable  locality  and  lays  the 
foundation  of  the  nest,  depositing  an  egg  in  each  of  the  first  few 
-cells.  The  grubs  hatch  out  quickly,  and  then  the  female  devotes 
all  her  attention  to  feeding  them,  bringing  at  first  sugary  material 
which  she  collects  from  flowers  or  from  any  store  she  is  able  to  rob. 
When  they  are  a  little  older,  she  chases  and  captures  living  insects 
of  different  kinds,  breaks  their  bodies  into  a  pulp  by  her  strong 
jaws  and  supplies  this  animal  diet  to  the  growing  young.  The 
first  set  of  young  mature  into  workers,  which  are  really  imperfect 
females,  and  these  at  once  devote  all  their  time  to  improving  and 
enlarging  the  nest,  and  to  foraging  for  and  tending  the  successive 
series  of  eggs  which  the  queen  continues  to  lay.  The  fossorial 
wasps  are  all  carnivorous  and  hunt  and  collect  insects,  caterpillars 
and  spiders  for  the  use  of  their  grubs.  The  females  do  all  the  work 
and  never  live  in  communities,  but  make  separate  cells  of  clay, 
burrows  in  soft  soil  or  tunnels  in  the  tissues  of  plants,  in  which 
to  place  their  eggs  and  store  of  victims.  The  Pompilidae  prey 
specially  on  spiders,  and  often  attack  large  and  poisonous  species. 
They  watch  for  them  at  the  entrance  of  the  holes  in  which  the 
spiders  lurk,  and  if  they  have  an  opportunity,  pull  one  out  by  the 
leg,  at  once  sting  it  between  the  poison  fangs  so  as  to  paralyse  these 
dangerous  weapons,  and  then  sting  again  in  the  soft  place  where 
the  abdomen  joins  the  front  part  of  the  body,  so  reducing  the  spider 
to  immobility.  The  wasp  then  makes  a  burrow  and  deposits  in  it 
the  helpless  spider  and  an  egg. 

In  the  communities  of  ants,  which,  unlike  those  of  wasps  and 
bees,  last  for  a  number  of  years,  there  are  usually  more  than  one 
queen  or  fertile  female.  The  eggs  hatch  out  into  little  grubs,  which 
are  fed  and  tended  by  the  workers  with  a  care  and  intelligence  far 
surpassing  the  qualities  displayed  by  any  other  invertebrate 
animals.  The  grubs  are  moved  from  place  to  place  in  the  nest 
according  to  temperature  or  moisture,  are  kept  clean,  and  are 
frequently  carried  above  ground  for  an  airing. 

Beetles  as  a  rule  lay  a  considerable  number  of  eggs,  and  do 
no  more  for  the  next  generation  than  choose  a  suitable  place  for 
the  larvae.  In  the  dung-beetles  special  provision  is  sometimes 
made.  The  common  scarabaeus  beetle  of  south  Europe  buries  dung 
for  its  own  consumption,  but  also  accumulates  a  large  mass  in  a 
subterranean  chamber,  in  the  middle  of  which  the  egg  is  deposited. 
In  other  dung-beetles,  each  female  lays  only  three  or  four  eggs  in 


LIMITATION  OF  FAMILIES  129 

the  course  of  the  season,  and  watches  over  her  young  until  they 
have  matured.  The  great  water-beetles  spin  cocoons  of  silk  in 
which  the  eggs  are  deposited,  and  suspend  them  to  a  leaf  or  water- 
weed.  The  sexton-beetles  bury  the  carcasses  of  small  animals  and 
lay  their  eggs  in  them.  Butterflies,  moths  and  most  of  the  true 
flies  and  bugs  present  every  gradation  from  the  almost  random 
deposition  of  a  very  large  number  of  eggs  to  the  careful  selection 
of  a  food- plant  or  food- material  on  which  the  eggs  are  laid,  the 
number  being  then  smaller.  Occasionally  the  eggs  are  deposited  in 
burrows  that  are  excavated  in  the  tissues  of  plants  or  in  wounds 
made  in  the  bodies  of  animals. 

Many  of  the  marine  molluscs  lay  enormous  numbers  of  eggs  and 
make  no  provision  for  the  young.  The  common  edible  oyster 
begins  to  breed  when  it  is  three  years  old,  and  the  spawning  season 
lasts  from  April  to  August,  beginning  rather  later  in  cold  years. 
The  eggs  hatch  out  inside  the  gill-chamber  of  the  parent  and  emerge 
as  little  free-swimming  larvae,  and  it  has  been  calculated  that 
from  three  hundred  thousand  to  six  millions  may  be  discharged 
by  one  oyster  in  a  single  season.  A  very  large  proportion  of  the 
embryos  perish,  for  they  die  unless  they  succeed  in  finding 
suitable  ground  to  fix  themselves  within  a  day  or  two.  Those 
that  adhere  to  some  solid  object,  such  as  a  piece  of  stone, 
lose  their  cilia  and  begin  to  grow  rapidly,  being  small  oysters 
about  an  inch  across  at  the  end  of  the  first  year  and  thereafter 
increasing  at  the  rate  of  about  an  inch  a  year.  In  the  common 
fresh- water  mussel,  although  the  number  of  eggs  is  still  very 
large,  being  from  fourteen  thousand  to  a  million,  development 
has  proceeded  further  before  the  embryos  are  discharged  from  the 
gill-chamber  of  the  mother.  The  ciliated  free-swimming  stage  is 
passed  through  before  hatching,  and  for  a  few  hours  the  tiny  embryo 
swims  about  inside  its  own  eggshell,  thus  recalling  the  free-swimming 
state  of  its  remote  marine  ancestors.  After  hatching,  the  embryo, 
still  within  the  gill-chamber  of  its  mother,  grows  into  a  peculiar 
larva  known  as  the  glochidium,  with  a  shell  consisting  of  two 
valves  hinged  together,  with  strong  teeth  on  the  free  margin  of 
each  shell  and  with  a  long,  sticky  thread  protruding  from  between 
the  shells.  These  larvae  are  then  ejected  by  the  mother  into  the 
water,  and  they  fall  in  masses  to  the  bottom,  the  long,  sticky  threads 
forming  a  tangled  mass,  like  the  web  of  a  spider.  Most  of  them 
die,  but  if  any  small  fish,  attracted  by  the  gelatinous  mass  of  larvae, 
come  near,  then  the  glochidia  become  excited,  flap  their  shells 

C.A.  I 


130  CHILDHOOD  OF  ANIMALS 

actively,  and  so  straighten  out  the  byssus  thread.  If  one  of  these 
threads  touches  a  fish,  it  adheres,  and  the  tangled  mass,  consisting 
perhaps  of  many  hundred  larvae,  is  dragged  behind  the  fish.  As  the 
fish  wriggles  about,  some  of  the  glochidia  are  sure  to  be  brought  in 
contact  with  it,  and  any  that  do  so  at  once  seize  hold  firmly  with 
the  toothed  edges  of  their  shells,  snapping  them  tightly  together. 
Those  that  have  laid  hold  of  a  hard  spine  soon  die  and  drop  off. 
Those  that  have  lighted  upon  one  of  the  gill  filaments  or  the  fleshy 
part  of  fin  or  tail  cause  a  slight  inflammation  in  the  tissues  of  the 
fish  and  by  the  growth  of  these  become  enclosed  in  a  cyst.  Within 
this  they  live  on  the  juices  of  their  host,  are  carried  about  by  it, 
and  go  through  the  rest  of  their  development  until  they  are  perfect 
little  mussels.  In  the  meantime,  just  as  a  thorn  that  has  not  been 
extracted  is  gradually  sloughed  out  of  the  human  skin,  so  the 
cysts  containing  the  mussels  are  set  free  from  the  fish,  and  the 
mussels  drop  into  the  mud  and  begin  the  normal  adult  life  of  their 
kind.  The  fish  that  are  chosen  as  the  walking  nurseries  and  feeding- 
ground  of  the  young  mussels  are  usually  sticklebacks,  but  minnows 
and  loach  serve  equally  well. 

In  very  many  molluscs,  such  as  the  common  limpet,  the  eggs  are 
discharged  directly  into  sea-water  without  any  kind  of  protection 
or  provision  for  the  young,  and  only  a  very  small  proportion  of  the 
enormous  numbers  produced  succeed  in  reaching  adult  life.  In 
others  the  numbers  are  much  reduced  and  the  eggs  are  enclosed  in 
special  cocoons  of  various  shapes,  whilst  a  nutritive  juice  is  placed 
in  the  cocoon  with  them.  In  the  common  whelk  these  cocoons  are 
globular,  and  over  a  hundred  of  them,  each  containing  about  a  dozen 
eggs,  are  stuck  together  in  a  rounded  mass.  The  embryos  which 
happen  to  develop  first,  however,  eat  their  slower  fellows,  so  that 
only  a  very  few  actually  leave  the  cocoons.  Various  devices,  such 
as  the  formation  of  floating  rafts  of  mucus,  often  curiously  shaped, 
are  adopted  by  other  marine  molluscs.  Many  of  the  fresh-water 
molluscs  fasten  their  eggs  in  strings  to  water-weeds,  whilst  a  few  of 
those  in  the  sea  carry  them  attached  to  their  own  shells.  Precisely 
as  such  provision  for  the  protection  of  the  young  becomes  more 
efficient,  the  number  produced  decreases.  In  Paludina,  a  common 
English  fresh- water  snail,  the  eggs  are  developed  inside  the  body 
of  the  mother,  and  the  young,  comparatively  few  in  number,  are 
not  born  until  they  are  plainly  young  snails. 

In  the  air-breathing  land  snails,  which  must  be  regarded  as  the 
most  highly  developed  members  of  the  group,  the  eggs  are  rather 


LIMITATION  OF  FAMILIES  131 

large,  sometimes  enormous,  have  stout  shells  and  enough  food-yolk 
for  the  nutrition  of  the  embryo  until  it  is  fully  formed.  The  numbers 
are  much  reduced  and  the  eggs  are  generally  hidden  in  some 
secluded  place,  in  nests  at  the  roots  of  plants,  covered  over  with  soil, 
or  wrapped  in  leaves  on  forest  trees.  In  some  of  the  snails  of  the 
Pacific  Islands  only  five  or  six  eggs  are  laid,  and  these  are  preserved 
in  a  special  chamber  near  the  mouth  of  the  shell  of  the  mother, 
where  they  remain  some  time  after  they  have  hatched  out  as  young 
snails. 

In  the  various  invertebrate  animals  the  limitation  of  families 
and  the  provision  for  the  young  are  chiefly  economic  in  character. 
The  supply  of  food  and  the  protection  afforded  the  young  during 
their  most  tender  stages  have  brought  about  a  greater  security 
that  the  species  will  be  maintained.  Incidentally,  however,  they 
have  been  associated  with  considerable  changes  in  the  mode  of 
growth  of  the  young.  As  these  have  no  longer  to  secure  their  own 
living,  it  is  possible  for  the  mode  of  development  to  be  more  direct 
and  for  various  ancestral  stages  to  be  cut  out.  It  has  led,  more- 
over, to  very  important  modifications  of  instincts.  We  think  of 
the  care  bestowed  by  parents,  and  especially  by  a  mother  on  the 
young,  as  springing  from  affection,  but  .it  happens  often  amongst 
invertebrates  that  such  care  is  devoted  to  offspring  that  the  parents 
will  never  see  and  exhibited  by  animals  to  which  it  is  difficult  to 
attribute  any  emotions.  The  emotional  quality  of  affection  really 
comes  later  than  the  duties  and  cares  and  devotion  of  maternity. 
It  is  a  consequence  and  not  a  cause  of  parental  care.  The  modifica- 
tion of  instinct  that  it  reveals  is  very  striking.  The  first  business 
of  any  animal  is  to  look  after  itself,  to  provide  for  its  wants,  to 
satisfy  its  own  appetites,  and  especially  in  the  case  of  carnivorous 
creatures  to  regard  every  living  and  moving  thing  as  prey  to  be 
seized  and  devoured.  The  mere  toleration  of  the  young  by  the 
mother  is  a  new  beginning  in  life,  and  is  the  foundation  of  many  of 
the  highest  qualities  displayed  by  the  highest  animals  and  by  man 
himself. 

The  relations  of  the  young  to  the  mother  are  less  surprising. 
They  are  a  continuation  of  the  organic  relation  by  which  the  young 
are  born  of  the  body  of  their  mother,  and  they  exist  and  become,  so 
to  speak,  a  habit  before  the  individuality,  the  physical  powers  and 
the  senses  and  aptitudes  of  the  young  are  really  awakened.  And 
so  in  the  same  way  the  relations  of  the  young  of  the  same  family 
to  each  other  precede  consciousness  and  real  individuality.  The 


i32  CHILDHOOD  OF  ANIMALS 

eggs  are  laid  in  a  mass,  in  the  same  cocoon  or  in  the  same  supply 
of  food,  and  the  young  grow  up  together  necessarily  tolerant  of 
each  other's  presence.  The  swarm  of  caterpillars  clustering  on  a 
single  branch,  the  globe  of  young  spiders  cohering  round  the  remains 
of  the  cocoon  at  first  mean  nothing  except  the  accident  of  contiguity. 
In  most  cases,  as  soon  as  the  individuals  have  reached  a  certain 
degree  of  development  or  of  size,  they  separate  if  they  are  vegetable- 
feeding  creatures,  or  begin  to  attack  each  other  and  so  forcibly 
separate  if  they  are  carnivorous.  But  the  existence  of  cannibal 
larvae,  even  as  rare  exceptions,  of  instances  where  the  first  larva  to 
be  developed  devours  its  fellows,  throws  into  stronger  light  one 
striking  result  of  the  economic  limitation  of  families  and  the 
compulsory  association  of  the  young*.  It  has  created  the  necessity 
for  a  modification  of  the  predatory  instincts  of  carnivorous  crea- 
tures and  has  led  to  the  existence  of  a  power  of  recognition  and 
selection.  Certain  things  in  the  surrounding  world  they  attack 
and  eat ;  other  things  are  taboo,  not  to  be  attacked  and  not  to 
be  eaten. 

The  most  important  result  of  the  institution  of  family  life 
amongst  invertebrates  is  the  appearance  of  the  social  communities 
of  termites,  bees,  wasps  and  ants.  The  termites  are  the  simplest 
case.  They  form  a  real  family,  and  all  the  individuals  are  potential 
males  and  females.  The  workers  and  soldiers  are  at  first  not  more 
than  young  animals  which  have  to  pass  a  period  of  servitude  in 
the  paternal  home,  ministering  to  the  needs  of  the  community, 
before  they  go  out  into  the  world  to  lead  their  own  lives.  From 
such  a  condition  has  come  about  the  strange  existence  of  individuals 
so  modified  for  their  early  duties  that  they  cannot  pass  on  to  the 
normal  duties  of  normal  individuals.  In  the  social  wasps  and  bees 
there  is  the  further  complication  that  only  females  are  selected  to 
do  household  work,  and  modified  so  that  they  lose  the  ordinary 
selfish  instincts  and  devote  themselves  entirely  to  the  purposes  of 
the  community,  whilst  the  males  develop  only  the  instincts  and 
capacities  of  sex,  and  when  they  have  served  their  purpose  are 
turned  out  to  die.  In  the  communities  of  ants,  as  in  termites, 
there  are  individuals  modified  to  serve  as  workers  and  as  soldiers, 
but,  as  in  wasps  and  bees,  these  are  all  arrested  females,  and  the 
males  are  used  only  for  the  purposes  of  sex.  The  colonies  of  ants 
last  a  much  longer  time  than  those  of  bees  and  wasps,  which 
are  annual,  and  this  has  given  the  possibility  of  a  more  intricate 


LIMITATION  OF  FAMILIES  133 

civilisation  being  developed  and  of  much  more  complex  instincts 
being  formed.  When  we  think  of  the  elaborate  ordering  of  a  com- 
munity of  ants,  of  the  care  devoted  to  the  young,  of  the  capture  of 
other  ants  and  their  use  as  slaves,  of  the  domestication  of  aphides 
and  their  use  as  milch  cows,  of  the  cultivation  of  fungi  to  be  used 
as  foods,  it  is  plain  that  there  is  nothing  comparable  until  we  reach 
the  highest  organisations  of  civilised  man.  And  yet  these  have 
come  about  as  a  by-product  of  the  formation  of  families. 


CHAPTER  IX 

BROOD-CARE  AND  LIMITATION  OF  FAMILIES  IN 
LOWER  VERTEBRATES 

| 

I  HAVE  already  mentioned  the  prodigious  fertility  of  many  fish. 
Most  of  the  bony  fish  lay  eggs  in  numbers  that  can  be  estimated 
only  in  figures  ranging  from  hundreds  of  thousands  to  millions. 
Those  in  the  ovary  of  a  ling  have  been  estimated  at  over  twenty- 
eight  millions  ;  in  a  turbot  of  only  seventeen  pounds  weight,  nine 
millions  ;  and  in  a  cod  of  twenty-one  pounds  weight,  six  millions. 
These  eggs  are  extremely  small  and  are  discharged  directly  into  the 
water  by  the  female,  after  which  she  takes  no  further  notice  of 
them.  They  are  known  as  pelagic — that  is  to  say,  whether  they 
are  shed  by  fishes  that  spend  their  lives  swimming  either  at  the 
surface  or  at  no  great  depth,  such  as  cod,  whiting,  hake  and  ling, 
mackerel,  pilchards  or  sprats,  or  by  fishes  which  live  on  the  mud  or 
sand  of  the  bottom,  they  speedily  rise  to  the  surface  and  float  in 
the  warmer  water  exposed  to  the  light  and  heat  of  the  sun.  They 
are  transparent,  almost  invisible  glassy  spheres,  each  buoyed  up 
by  a  clear  droplet  of  oil.  At  the  usual  spawning  time,  April  or 
May  in  northern  waters,  the  whole  surface  of  the  sea  is  turbid  with 
the  innumerable  floating  eggs  and  newly-hatched  young,  in  the 
favourite  places  for  breeding,  which  are  usually  the  rough  waters 
of  bays,  or  near  shoals  on  which  the  tides  break.  The  eggs  contain 
very  little  food-yolk,  and  the  tiny  fish,  as  soon  as  they  hatch,  have 
to  begin  feeding  themselves.  They  are  omnivorous,  and  find  an 
abundant  Drey  in  the  still  more  innumerable  young  stages  of  various 
crustaceans,  molluscs  and  worms.  The  destruction  is  enormous  ; 
the  larger  fishes  devour  the  smaller  ;  great  flocks  of  sea-birds, 
gulls,  guillemots  and  gannets,  scream  and  squabble  as  they  gorge 
on  the  larger  fish  ;  whilst  whales  and  dolphins  come  to  join  at  the 
feast.  Other  agencies  share  in  the  work  of  destruction  ;  a  heavy 
night-frost,  a  torrent  of  rain,  or  a  storm  of  wind  may  destroy 
millions. 

Other  kinds  of  fish  descend  to  the  bottom  of  the  sea  and  lay 

134 


LIMITATION  IN  LOWER  VERTEBRATES      135 

submerged  or  demersal  eggs.  These  are  larger  and  are  heavier  than 
sea-water.  Herrings,  although  they  swim  near  the  surface,  lay 
demersal  eggs,  and  a  similar  habit  has  been  adopted  by  the  wolf- 
fish,  gobies,  suckers  and  many  others.  A  certain  amount  of  choice 
is  shown  in  the  selection  of  the  ground  for  depositing  the  eggs,  and 
these  are  usually  enclosed  in  a  firm  and  sticky  capsule,  or  embedded 
in  lumps  of  mucus  which  enables  them  to  adhere  to  seaweed  or 
stones.  The  numbers  are  much  smaller,  and  are  to  be  counted  in 
thousands,  hundreds  or  dozens.  The  herring,  which  is  the  most 
prolific  of  these  fish  with  demersal  eggs,  deposits  about  twenty 
thousand.  Fishes,  like  salmon,  which  ascend  rivers  from  the  sea, 
and  most  of  the  fresh-water  fish,  are  also  demersal,  and  many 
of  them  show  a  certain  amount  of  care  in  the  deposition 
of  the  eggs,  scooping  out  holes  and  covering  them  with  sand  or 
stones. 

There  is  a  heavy  toll  taken  of  unprotected  demersal  eggs,  and 
there  are  many  remarkable  instances  in  which  brood-care  goes 
much  beyond  the  mere  choice  of  a  locality  for  laying  the  eggs.  The 
spawn  is  often  sedulously  guarded  by  one  of  the  parents,  and  it  is 
interesting  that  this  duty  is  almost  invariably  assumed  by  the  male. 
The  common  British  butter-fish  (Pholis  gunnellus)  coils  its  body 
round  the  mass  of  eggs,  the  male  and  female  relieving  one  another 
in  this  task,  and  then,  after  a  time,  hiding  them  in  holes  scooped  in 
the  rocks  by  some  of  the  boring  molluscs.  The  female  lump-sucker 
attaches  her  eggs  in  sticky  masses  to  rocks  or  logs  and  then  takes 
no  further  interest  in  them,  but  the  male  watches  over  them  until 
they  hatch  out,  when  the  fry  cling  to  his  body  by  their  suckers. 
The  sand-goby  lays  her  eggs  under  the  empty  shell  of  a  shellfish, 
such  as  the  scallop,  and  then  the  male  watches  over  them  until  they 
hatch.  J.  S.  Budgett,  who  went  to  the  Gambia  to  study  the  strange 
African  lung -fish,  Protopterus,  found  that  the  eggs  were  laid  in 
circular  nests  hollowed  in  the  mud  on  the  edges  of  swamps.  The 
nest  was  an  irregular  hole  about  a  foot  deep,  filled  with  water,  but 
unlined.  It  was  surrounded  by  reeds,  and  these  were  crushed  down 
at  one  side,  there  being  a  sort  of  path  by  which  the  parent  could 
pass  out  and  in  across  the  little  stretch  of  dried  mud  separating 
the  nest  from  the  swamp.  The  female  apparently  deserted  the 
nest  after  laying  the  eggs,  but  the  male  stayed  on,  and  was  usually 
found  lashing  his  tail  and  keeping  the  water  in  violent  commotion, 
so  that  it  was  better  aerated.  The  male  guarded  the  young  larvae 
savagely,  biting  at  any  one  who  tried  to  touch  them.  The  young 


136  CHILDHOOD  OF  ANIMALS 

larvae  grew  suckers  on  their  heads  like  those  of  tadpoles,  with 
which  they  fastened  themselves  to  the  sides  of  the  nest.  In  the 
same  locality  Budgett  found  the  floating  nests  of  Gymnarchus 
niloticus,  which  were  a  foot  and  a  half  across  and  surrounded  on 
three  sides  with  a  rim  of  twisted  weeds,  the  fourth  side  being 
under  the  level  of  the  water.  The  male  kept  a  fierce  watch  over 
the  larvae  in  the  nest,  snapping  viciously  at  intruders.  The 
fantang  (Heterotis  niloticus)  makes  a  nest  four  feet  across  with  a 
rim  eight  inches  high,  composed  of  the  stems  of  grasses.  In 
making  its  nest  the  fish  swims  round  and  round,  throwing  its  tail 
upwards  and  outwards,  and  so  tossing  on  the  growing  wall  the 
debris  it  removes  from  the  central  area.  Soon  after  the  larvae 
hatch  they  are  taken  put  on  trial  swimming  trips  by  the  parent, 
but  return  to  their  home.  When  they  leave  it  finally,  the  parent 
still  keeps  with  them  for  a  time.  The  bow-fin  of  the  great  lakes  of 
America  leaves  deep  water  in  spring  and  moves  to  swampy  shallows. 
There  they  break  up  into  little  parties,  each  consisting  of  a  female 
and  several  males.  The  fish  of  one  party  construct  a  rude  nest 
by  wriggling  round  and  round  in  the  mud  until  they  clear  a  circular 
area.  In  these  the  eggs  are  laid,  and  one  of  the  males  mounts 
guard,  the  rest  of  the  party  dispersing.  When  the  young  finally 
leave  the  nest,  they  are  accompanied  and^ protected  by  the  guardian 
parent  for  a  time. 

The  American  bullheads  or  horned  pouts  resort  in  pairs  to  the 
muddy  shallows  at  the  edges  of  the  fresh- water  lakes  they  inhabit. 
In  water  a  few  inches  deep  they  gradually  make  a  hollow  in  the 
side  of  the  bank,  throwing  out  the  mud  and  sand  until  a  mound  is 
formed  on  the  bottom  with  a  shallow  groove  leading  to  the  opening 
into  the  nest.  The  excavation  is  done  with  the  head,  and  although 
both  male  and  female  share  in  the  work,  the  latter  is  more  zealous. 
Sometimes  the  nests  are  made  in  the  hollow,  submerged  stumps  of 
trees,  sometimes  scooped  out  amongst  reeds  and  bulrushes.  After 
the  eggs  are  laid,  one  or  both  parents  remain  to  guard  the  young 
larvae,  and  then  swim  out  with  the  shoals  of  little  fish.  Shoals 
from  different  nests  have  been  observed  to  join  temporarily,  but 
afterwards  to  separate,  so  that  it  seems  as  if  the  corporate  life  had 
led  to  a  definite  sense  of  recognition  amongst  the  members  of  each 
brood. 

The  nesting  habits  of  the  little  sticklebacks  which  live  in  fresh, 
brackish  or  salt  water  are  well  known.  The  male  is  the  house- 
builder,  and  uses  weeds  and  twigs  as  his  material,  fastening  them 


LIMITATION  IN  LOWER  VERTEBRATES      137 

together  with  a  sticky  secretion  from  the  kidneys.  When  the 
female  has  deposited  her  eggs  in  the  nest,  she  deserts  it,  and  the 
male  continues  to  guard  nest,  eggs  and  young  fry  with  the 
most  pugnacious  spirit.  The  larger  stickleback  of  salt  water  has 
similar  habits,  building  a  nest,  in  sheltered  pools,  of  seaweeds  and 
plantlike  colonies  of  hydroids.  In 
the  brightly  coloured  marine  wrasses, 
both  sexes  join  to  build  the  nests, 
which  are  constructed  of  broken  shells, 
seaweeds  and  other  debris.  The  great 
masses  of  gulf -weed  forming  the  "  Sar- 
gasso Sea  ' '  in  the  areas  affected  by 
the  Gulf  Stream  are  a  preserve  for 
marine  creatures  which  drift  about 
in  the  protection  of  the  weed.  Amongst  these, 
the  marbled  angler  (Antennarius  marmoratus) , 
a  small  fish  that  rests  on  the  weed  with  almost 
armlike  pectoral  fins,  constructs  a  globular  nest 
supported  by  silky  fibres,  within  which  the 
eggs  are  suspended  in  bunches. 

A  few  fishes  reduce  the  number  of  the  family 
still  further  and  protect  it  by  carrying  about 
the  eggs  and  young  larvae.  The  well-known 
sea-horse  (Hippocampus)  (Fig.  28),  which  carries 
itself  erect  when  swimming  and  looks  like  the 
knight  of  a  chess  board,  has  a  pouch  in  the 
male,  on  the  front  of  the  body  opposite  the 
root  of  the  tail,  and  in  this  the  eggs  and 
young  larvae  are  carried  about.  The  pipefish, 
which  is  sometimes  found  amongst  whitebait,  pouch.  (After MURRAY.) 
has  a  similar  pouch,  which,  however,  is  longer 
and  narrower,  to  suit  the  different  shape  of  the  body.  In  Soleno- 
stomus,  which  inhabits  the  Pacific  and  Indian  Oceans,  there  is  a 
similar  pouch,  but  carried  by  the  females,  and  formed  of  the  ventral 
fins.  Most  of  the  catfish  protect  their  young  by  making  nests  and 
guarding  them  with  fury,  more  often  the  male,  as  Aristotle  observed 
in  the  case  of  the  European  catfish  (Silurus  glanis),  but  sometimes 
the  female,  sometimes  both  sexes,  performing  this  duty,  and  after- 
wards herding  the  shoals  of  fry  when  they  emerge.  In  a  few  cat- 
fish the  number  of  eggs  is  still  further  reduced,  and  the  male  or 
the  female,  according  to  the  species,  carries  them  in  the  mouth  and 


138  CHILDHOOD  OF  ANIMALS 

pharynx,  a  very  singular  case  of  the  subordination  of  the  normal 
appetite  to  an  unselfish  duty.  In  the  cichlids  the  same  habit  has 
been  developed,  but  most  usually  by  the  females.  In  Aspredo,  a 
large  fish  found  in  Guiana,  there  is  a  still  more  remarkable  mode  of 
brood  protection.  The  skin  of  the  under  surface  of  the  body,  over 
the  head,  abdomen  and  paired  fins  becomes  soft  and  spongy,  and 
the  eggs  adhere  to  this  in  a  single  layer  ;  whilst  the  skin  of  the 
mother  forms  cup-shaped  receptacles  richly  supplied  with  blood- 
vessels, and  suggesting  that  the  young  embryos  obtain  nourishment 
by  a  kind  of  placental  connection.  In  the  small  fresh- water 
bitterling  of  Europe,  the  female  develops  a  very  long  tube  at  the 
end  of  which  is  the  orifice  by  which  the  eggs  leave  the  body.  She 
uses  this  as  an  ovipositor,  inserting  it  between  the  valves  of  the 
shells  of  fresh-water  mussels  and  discharging  the  eggs  into  the 
branchial  cavities  of  these  animals,  within  which  they  go  through 
their  development  in  security. 

In  nearly  all  the  bony  fish  the  eggs  are  fertilised  after  they  have 
left  the  body  of  the  mother,  and  their  subsequent  development, 
whether  they  are  turned  adrift  or  guarded  in  some  of  the  curious 
ways  I  have  mentioned,  is  really  independent  of  her.  But  in  a 
few  instances  not  only  is  there  internal  fertilisation,  but  a  large 
part  of  the  development  takes  place  in  the  ovary  of  the  mother, 
and  the  young  larvae  are  fed  not  only  by  the  small  amount  of  yolk 
deposited  in  the  egg,  but  by  a  secretion  from  the  walls  of  the 
ovary  which  they  swallow  and  digest.  The  blenny  is  the  best- 
known  case  of  this  device.  The  eggs  are  hatched  in  about  twenty 
days,  but  the  young  are  not  actually  born  until  they  are  several 
months  old,  by  which  time  they  are  nearly  two  inches  long  and 
are  like  the  parents  except  in  size. 

In  all  Elasmobranch  fishes,  fertilisation  is  internal  and  the  eggs 
are  very  large  and  few  in  number.  The  breeding  season  extends 
over  the  greater  part  of  the  year,  and  only  one  or  two  eggs  are 
ripened  at  a  time.  After  it  has  been  fertilised,  the  egg  is  enclosed 
in  a  brown  horny  case,  often  oddly  shaped,  usually  oblong  or 
quadrangular,  with  a  hook  or  long  tendril  at  each  corner.  In  some 
rays  and  the  common  English  spotted  dogfish  these  egg-cases  are 
deposited  on  the  sea-bottom,  or  their  tendrils  are  twisted  round  a 
strand  of  seaweed.  The  secure  position  and  the  large  and  un- 
palatable case  protect  the  developing  embryos  for  several  months, 
after  which  the  young  fish,  now  able  to  look  after  themselves,  escape 
through  a  slit  in  the  egg-case.  In  most  of  the  dogfishes,  as,  for 


LIMITATION  IN  LOWER  VERTEBRATES      139 

instance,  in  the  common  smooth-hound,  in  many  rays  and  in  sharks, 
the  egg-case  is  very  thin  and  delicate,  the  quantity  of  food-yolk  in 
the  egg  is  much  less,  and  the  eggs  are  retained  in  the  body  of  the 
mother,  lodged  in  special  expansions  of  the  oviducts,  until  the 
embryos  have  hatched  and  grown  to  young  fish.  The  walls  of 
these  sacs  form  long  filaments,  supplied  with  blood  from  the  vessels 
of  the  mother  and  serving  for  the  nutrition  of  the  young.  In  some 
cases  this  secretion  is  swallowed  by  the  embryo  in  the  same  way  as 
in  the  viviparous  blenny.  In  other  cases,  the  nutritive  filaments 
of  the  mother  are  arranged  in  a  pair  of  bundles,  one  of  which  is 
thrust  through  each  spiracle  of  the  embryo  into  its  alimentary 
canal,  where  the  nutritive  secretion  is  taken  up.  There  is  a  still 
higher  development  of  this  mode  of  maternal  nutrition  of  the 
embryo  in  some  of  the  sharks,  which  recalls  the  embryonic  stages 
of  mammals.  The  blood-vessels  of  the  embryo  grow  out  over  the 
yolk-sac,  and  absorb  the  yolk  and  use  it  for  the  growth  of  the 
embryo.  When  the  yolk-sac  is  exhausted  of  its  contents,  the  blood- 
vessels covering  it  grow  out  into  tufts  which  intertwine  with  similar 
vascular  tufts  arising  from  the  tissues  of  the  mother,  and  through 
such  a  placental  connection  the  blood  of  the  mother  conveys 
nutrition  to  the  embryo. 

Thus  in  various  ways  and  by  many  different  devices  the  number 
in  each  brood  of  fishes  becomes  reduced  in  many  species.  Instead 
of  an  enormous  number  being  discharged  to  take  their  own  chance, 
a  few  are  protected,  sometimes  fed,  and  only  set  free  when  they 
have  attained  some  degree  of  strength  and  capacity  for  protecting 
themselves.  As  in  lower  animals,  apart  from  its  consequences  in 
better  securing  the  maintenance  of  the  species,  this  changed  mode 
of  reproduction  has  a  number  of  by-products.  The  growth  of  the 
protected  embryos,  especially  when  they  are  supplied  with  much 
food,  either  in  the  form  of  yolk  or  later  on  from  the  tissues  of  the 
mother,  is  more  direct  and  less  a  repetition  of  the  ancestral  history. 
The  instincts  of  the  guardian  parent  or  parents  have  become  diverted 
to  new  directions.  Instead  of  being  occupied  throughout  their 
whole  lives  with  their  own  individual  concerns;  the  parents  devote 
some  time  and  much  trouble  to  matters  which  affect  the  safety  of 
the  species  rather  than  their  own  individual  safety.  They  take 
substances  into  the  mouth,  such  as  eggs,  which  would  be  good  to 
eat  and  yet  do  not  eat  them.  They  watch  over,  swim  about  with 
and  protect  from  others  little  moving  creatures  which  a  few  weeks 
before  or  a  few  weeks  afterwards  they  would  greedily  devour. 


140  CHILDHOOD  OF  ANIMALS 

The  young,  too,  occupying  the  same  nest,  swimming  in  the  same 
shoal  and  following  the  same  guardian,  acquire  some  power  or 
habit  of  association  which,  if  it  were  conscious,  we  should  call 
recognition. 

Later  on  most  fishes  break  away  from  the  shoal  and  live  strictly 
individual  lives,  but  there  are  not  a  few  which  continue  to  move 
in  masses  throughout  their  lives,  showing  concerted  action  and  a 
feeble  beginning  of  the  social  instinct. 

Most  of  the  tailless  batrachians,  the  frogs  and  toads,  and 
many  of  the  tailed  batrachians,  the  newts  and  salamanders,  lay 
a  very  large  number  of  eggs,  and  exercise  the  least  possible  dis- 
crimination in  their  selection  of  a  spawning-ground.  The  common 
British  grass  frog  (Rana  temporaries)  breeds  very  early  in  spring,  and, 
no  doubt  attracted  by  the  relative  warmth  of  the  water,  chooses 
the  shallow  edges  of  ponds,  or  temporary  pools  which  may  dry  up 
in  a  few  days  and  leave  the  spawn  stranded.  The  natterjack  toad 
(Bufo  calamita)  lives  in  sandy  places,  heath  land,  maritime  dunes 
and  so  forth,  and  deposits  its  masses  of  spawn  in  the  nearest  water 
it  can  find,  being  content  with  the  temporary  rainpools  in  cart-ruts. 
These  toads  are  common  on  many  of  the  Surrey  heaths  near  London, 
where  they  may  breed  from  April  until  July,  and  only  a  very  small 
proportion  of  the  eggs  laid  succeed  in  developing.  The  common 
toad  (Bufo  vulgaris)  limits  its  breeding,  at  least  in  England,  to  a 
few  weeks,  from  the  middle  of  March  to  the  end  of  April,  according 
to  the  season,  and  moves  great  distances  to  particular  favoured 
places,  generally  deep  pools  in  quarries,  where  it  deposits  its  eggs 
in  much  more  favourable  conditions.  Nearly  all  the  tailless 
batrachians  live  in  or  near  the  water,  and  the  eggs,  which  are  very 
numerous,  are  deposited  in  water  with  no  special  precautions.  In 
a  few,  such  as  the  spotted  salamander,  the  eggs  are  retained  in  the 
body  of  the  female  until  they  have  actually  hatched  or  are  on  the 
point  of  hatching  ;  whilst  some,  such  as  Amphiuma  and  the 
Ccecilians,  lay  their  eggs  on  land  and  protect  them  by  coiling  their 
bodies  round  them. 

Amongst  the  tailless  forms,  however,  brood-care  may  reach  a 
much  higher  level,  with  a  consequent  reduction  in  the  number  of 
the  young.  Hyla  faber,  a  Brazilian  tree-frog,  descends  to  the  water 
to  breed,  a  male  and  female  associating,  but  only  the  female  pre- 
paring the  nursery  for  the  young.  She  selects  the  shallow  end  of 
a  pool  and  dives  to  the  bottom,  bringing  up  loads  of  mud  on  her 
head,  which  she  gradually  piles  up  to  form  the  circular  wall  of  a 


LIMITATION  IN  LOWER  VERTEBRATES     141 

tiny  pond,  smoothing  it  with  her  hands  on  the  inside  and  continuing 
her  labours  until  the  edge  is  raised  above  the  surface  of  the  water. 
The  spawn  is  deposited  in  this  little  nest  and  the  parents  lurk  near 
it  for  some  days,  but  appear  to  take  no  special  precautions  for 
guarding  the  young.  In  other 
cases  the  eggs  are  laid  out 
of  the  water,  in  holes  or  under 
grass,  so  that  they  are  saved 
from  aquatic  enemies  in  their 
early  stages,  and  the  tadpoles 
are  washed  into  the  water  by 
rain  after  they  have  emerged 
from  the  egg.  Phyllomedusa 
iheringi,  a  Brazilian  frog,  also 
deposits  her  eggs  out  of  water. 
A  male  and  female  leave  the 
water  together,  climbing  up 
on  flat  leaves,  one  of  which 
the  two  animals  hold  twisted 
to  a  funnel.  The  female  de- 
posits a  mass  of  eggs  in  this, 
and  their  sticky  surface  ad- 
heres to  the  leaf,  leaving  it 
folded  round  the  mass.  After 
the  formation  of  this  simple 
nest,  there  is  no  further  pro- 
vision for  the  young,  and  the 
tadpoles,  when  they  emerge, 
have  to  wriggle  down  into 
the  water.  The  male  of  the 
midwife  toad  (Alytes  obstetri- 
cans),  a  common  batrachian 
in  Europe,  winds  a  string  of 
eggs  round  his  hind-legs,  im- 
mediately after  they  have  been  laid,  and  then  retreats  to  a  hole. 
At  night  he  comes  out  to  feed,  and  at  the  same  time  moistens 
the  eggs,  sometimes  carrying  them  down  to  water  and  dipping 
them  in  it.  After  three  weeks  of  nursing  them  in  this  careful 
way,  the  male  carries  them,  now  ready  to  hatch,  down  to  the 
water,  where  the  tadpoles  emerge,  and  his  responsibility  ends. 
In  Rhinoderma  darwini  (Fig.  29),  a  small  frog  discovered  by  Darwin 


FIG.  29.  Darwin's  Rhinoderma,  showing 
Brood-pouch.  The  frog  has  been  dis- 
sected from  the  ventral  side  ;  the  skin  on 
the  right  has  been  cut  away,  showing  the 
opening  from  the  mouth  to  the  pouch, 
the  posterior  half  of  which  has  been 
opened  to  show  the  young  frogs.  (After 
HOWES;  enlarged.) 


142  CHILDHOOD  OF  ANIMALS 

in  Chili,  the  male  has  a  pair  of  sacs,  normally  used  to  increase  the 
volume  of  the  voice,  which  open  into  the  mouth  on  each  side  of 
the  tongue.  In  the  breeding  season  the  fertilised  eggs,  which  are 
only  from  five  to  fifteen  in  number,  are  placed  in  this,  and  as  the 
embryos  develop,  the  sacs  expand  until  they  occupy  the  whole  of 
the  lower  surface  of  the  body  under  the  skin.  Not  only  hatching 
takes  place  in  this  secure  retreat,  but  also  the  further  development 
of  the  young,  which  do  not  emerge  until  they  are  miniatures  of  the 
adult.  In  Rhacophorus  reticulatus,  a  Ceylonese  tree-frog,  there  are 
only  about  twenty  eggs  produced,  and  these  after  being  laid  are 
attached  to  the  under  surface  of  the  skin  of  the  female,  where  they 
are  carried  about  in  little  pits,  until  the  tadpoles  hatch  out.  In  the 
Surinam  toad,  the  male  spreads  the  eggs,  which  are  also  few  in 
number,  on  the  back  of  the  female,  where  each  sinks  into  a  little 
cup-shaped  depression,  afterwards  covered  by  a  lid,  and  are  thus 
carried  about  until  the  metamorphosis  is  completed.  In  Hyla 
goeldii,  a  South  American  tree-frog,  there  are  between  twenty  and 
thirty  large  eggs,  which  are  carried  on  the  back  of  the  mother, 
supported  by  a  flap  or  fold  of  the  skin  ;  and  in  the  tree-frogs  of  the 
genus  Nototrema,  which  also  live  in  South  America,  the  females 
have  a  well-developed  pouch  of  the  skin,  placed  on  the  back  and 
opening  backwards,  in  which  the  eggs  are  carried  until  they  are 
either  tadpoles  or  young  frogs. 

In  all  reptiles  the  number  of  the  family  has  been  greatly  re- 
duced, and  not  more  than  from  six  or  seven  to  about  one  hundred 
are  produced  at  a  time,  except  in  some  of  the  turtles  and  tortoises. 
The  eggs  are  large,  containing  enough  food-yolk  to  nourish  the 
embryo  until  it  is  hatched  in  a  condition  closely  resembling  that 
of  the  parent,  except  in  size  and  pattern,  but  large  and  strong  enough 
to  look  after  itself.  In  consequence  of  this,  the  old  larval  stages  are 
suppressed,  and  although  the  embryo  passes  through  a  phase  when 
it  has  gill  slits  and  the  appearance  of  an  aquatic  creature,  this 
takes  place  before  hatching,  and  the  young  are  terrestrial.  Even 
the  aquatic  reptiles  come  on  land  to  breed,  and  there  are  no 
more  than  vague  reminiscences  of  their  gill-breathing  ancestors. 
The  eggs  are  enclosed  in  a  firm  shell,  sometimes  tough  and  leathery, 
sometimes  hard  and  brittle,  but  nearly  always  white  in  colour.  In 
most  cases,  the  eggs  are  hatched  outside  the  body,  but  in  a  few 
snakes  and  lizards  they  are  retained  until  the  young  are  born,  in 
these  cases  the  shells  being  very  thin.  Brood-care  is  almost  com- 
pletely confined  to  a  choice  of  the  place  in  which  the  eggs  are  to  be 


LIMITATION  IN  LOWER  VERTEBRATES      143 

laid,  and  the  formation  of  a  nest  or  burrow  to  contain  them.  The 
females  alone  perform  this  duty,  and  although  in  certain  cases  the 
mothers  exercise  some  guardianship  over  the  young  after  birth  or 
hatching,  the  males  take  no  interest  in  them. 

All  the  turtles  and  tortoises  lay  white  eggs  with  a  stout  shell, 
which  may  be  thick  and  hard,  or  leathery.  The  females  usually 
make  a  hole  in  the  ground,  in  some  well-chosen  locality,  to  which 
they  return  year  after  year,  and  are  at  the  pains  to  cover  up  the  eggs 
and  so  far  as  possible  remove  all  trace  of  their  presence — &  necessary 
precaution,  as  they  are  a  favourite  food  of  many  different  kinds  of 
animals.  The  female  common  European  pond- tortoise  selects  a  piece 
of  hard  bare  ground,  which  she  moistens,  and  then  bores  a  hole  in 
it  with  her  tail,  afterwards  enlarging  the  cavity  with  her  hind  limbs 
until  it  is  several  inches  deep.  The  eggs  are  placed  in  this  and  then 
the  hole  is  filled  up  with  earth  and  firmly  stamped  down  so  as  to 
leave  no  trace  of  the  disturbance.  The  huge  loggerhead  turtle, 
which  lives  in  the  warm  seas  of  both  hemispheres,  comes  ashore  to 
breed,  and  has  been  watched  on  the  Florida  coast.  The  female 
scoops  a  hole  in  the  sand,  above  tide  mark,  places  the  eggs  in  it,  and, 
having  covered  them  over,  returns  to  the  sea  and  takes  no  further 
notice  of  them.  The  young  hatch  out  in  six  or  eight  weeks  and  at 
once  take  to  the  water,  selecting  shallow  rock  pools.  There  is 
great  destruction  of  the  young  and  of  the  eggs,  and  an  unusually 
large  number  of  these  is  laid,  sometimes  as  many  as  a  thousand. 
The  green  or  edible  turtle  has  similar  habits,  but  is  more  careful 
and  lays  as  a  maximum  a  hundred  eggs.  The  females  come  from 
great  distances  to  well-chosen  breeding-places  on  sheltered  sandy 
shores.  They  are  shy  and  wary,  looking  for  the  presence  of  any 
possible  foes  before  they  venture  to  land.  Finally  they  proceed 
just  beyond  tide-level,  scoop  out  deep  holes,  lay  the  eggs,  cover 
them  up  and  carefully  smooth  over  the  heap  of  sand  that  they  have 
dug  out,  to  leave  no  traces  of  their  operations,  and  are  said  to 
return  to  the  sea  by  a  circuitous  route,  so  that  their  nests  cannot 
be  tracked  out  by  the  trail  they  leave  on  the  beach.  Box  tortoises 
lay  a  small  number  of  eggs  and  secrete  them  in  soft  ground  or  under 
leaves  so  carefully  that  the  young  have  very  seldom  been  found. 
The  female  of  the  common  Greek  tortoise,  which  is  often  kept  as  a 
pet,  lays  from  two  to  four  eggs  rather  late  in  summer,  and  buries 
them  carefully  in  the  ground.  Soon  after  the  young  emerge  they 
bury  themselves,  and  do  not  reappear  until  next  spring.  The 
South  American  "  Arrau  "  turtle,  the  eggs  of  which  are  taken  in 


144  CHILDHOOD  OF  ANIMALS 

great  quantities  chiefly  because  of  the  oil  which  is  extracted  from 
them,  has  the  curious  habit  of  laying  in  communal  nests.  At  the 
breeding  season,  the  females  leave  the  water  and  go  to  sandy  banks, 
generally  on  islands  in  the  rivers.  A  female  excavates  a  hole  about 
three  feet  deep  and  lays  over  a  hundred  eggs  in  it,  covering  them  up 
with  sand.  A  second  and  a  third  female  then  lay  their  eggs  in 
successive  layers,  covering  them  up,  and  so  on  until  the  hole  is 
filled.  The  female  soft-shelled  turtle  of  the  Southern  States  of 
North  America  leaves  the  water  and  selects  a  suitable  bank,  into 
which  she  burrows,  remaining  for  several  days  with  only  her  snout 
protruding.  During  this  time  she  lays  several  dozen  eggs,  and 
then  crawls  out  carefully  so  as  to  leave  them  covered  up. 

In  crocodiles  and  alligators  brood-care  is  further  advanced.  The 
eggs  are  large,  oval  and  hard-shelled  and  are  laid  in  a  carefully 
selected  or  prepared  place,  out  of  the  water,  and  both  the  eggs 
and  the  young  are  frequently  savagely  protected  by  the  mother. 
The  Indian  gharial  digs  a  nest  in  the  dry  sand,  arranging  the  eggs 
in  layers  and  carefully  covering  them.  The  Nilotic  crocodile  makes 
a  circular  nest  in  the  sand  about  two  feet  deep,  with  a  raised  floor 
and  undercut  walls,  so  that  the  eggs  when  they  are  laid  roll  from 
the  centre  under  the  protection  of  the  wall.  The  first  layer  is 
covered  with  sand  and  a  second  layer  then  added,  and  the  whole 
covered  up.  The  mother  remains  on  the  nest  to  guard  it,  returning 
to  it  after  her  visits  to  the  water  in  search  of  food.  When  the 
young  are  nearly  ready  to  hatch,  they  make  a  barking  noise  inside 
the  shell ;  this  is  said  to  attract  the  attention  of  the  mother  and 
to  bring  her  back  to  the  nest.  She  takes  the  young  to  the  water 
when  they  have  hatched  and  guards  them  against  their  many 
enemies  for  a  considerable  time.  The  female  of  the  Mississippi 
alligator  makes  a  nest  of  leaves  and  soil  a  few  feet  high  and  deposits 
several  layers  of  eggs,  afterwards  covering  them.  She  is  said  to 
take  no  further  notice  of  the  young  when  they  are  hatched. 

The  young  of  all  the  alligators  and  crocodiles  are  hatched  in  a 
lively  and  vigorous  condition,  and  are  able  to  snap  rather  savagely 
almost  before  they  leave  the  shell.  I  have  personal  experience 
only  of  young  alligators.  These  are  very  easily  tamed,  and  quickly 
learn  to  distinguish  between  persons,  taking  dislikes  to  individuals 
and  always  snapping  at  them  and  refusing  to  be  handled,  whilst  with 
others  they  are  gentle  and  docile.  They  make  a  loud  barking  noise 
to  attract  attention.  It  is  known  that  the  mothers  protect  the 
young  in  the  case  of  some  species  of  crocodiles,  and  I  am  inclined 


LIMITATION  IN  LOWER  VERTEBRATES     145 

to  think  that  this  happens  in  most  of  the  species.  In  any  case  the 
newly  hatched  young  remain  together  for  a  time,  and  tolerate  each 
other's  presence.  Healthy  crocodiles  and  alligators,  young  or  old, 
are  rather  savage  creatures,  when  the  water  in  which  they  are  kept 
is  not  so  cold  that  they  are  torpid.  They  are  ready  to  snap  at  any 
moving  object,  or  even  at  a  piece  of  wood  thrown  into  their 
pool.  And  yet,  although  there  are  occasional  accidents,  they  are 
gregarious,  seldom  attacking  one  another  savagely  unless  in  an 
actual  struggle  for  food.  Individuals  of  all  sizes  and  of  several 
kinds  may  be  kept  safely  together.  This  instinct  of  toleration  for 
their  own  kind  is,  no  doubt,  the  result  of  the  association  of  the 
young  with  each  other  and  with  the  mother.  The  voice  is  certainly 
used  as  a  recognition  call.  The  strong  musky  odour,  due  to  a 
secretion  from  glands  at  the  root  of  the  tail,  but  which  pervades  the 
whole  body,  may  possibly  also  serve  for  recognition,  but  I  have 
never  been  able  to  detect  the  odour  in  young  animals. 

Lizards  lay  relatively  large  eggs,  the  numbers  varying  from  two 
to  twenty  or  thirty.  The  process  cf  incubation  takes  a  long  time, 
and  when  the  young  creatures  emerge  they  are  fully  formed, 
differing  from  their  parents  only  in  size  and  colour.  They  are 
usually  white,  or  very  pale,  and  lie  quietly  for  a  few  days,  and  then 
set  about  the  business  of  life  without  any  assistance  or  guardian- 
ship from  their  parents.  Little  trouble  is  taken  even  about  the 
deposition  of  the  eggs.  They  are  usually  placed  in  holes  on  the 
ground,  in  heaps  of  leaves,  or  in  any  natural  cavities.  A  certain 
number  are  viviparous — that  is  to  say,  the  eggs  hatch  just  before 
they  are  laid.  The  slow-worm,  one  of  the  common  English  lizards 
(Lacerta  vivipara),  some  of  the  chameleons  and  many  of  the  skinks 
are  viviparous.  Thus  although  brood -care  among  lizards  is  passive, 
the  large  size  of  the  eggs  and  still  more  the  occasional  viviparous 
habit  secure  that  the  newly  hatched  or  born  creatures  are  mature 
enough  to  be  independent,  and  the  number  of  the  family  has  been 
reduced. 

The  eggs  of  snakes  are  large,  usually  very  elongated  and  en- 
closed in  a  soft,  but  tough,  shell.  They  are  not  very  numerous, 
varying  from  three  or  four  to  fifty.  They  are  fertilised  before  they 
leave  the  body  of  the  mother,  but  the  length  of  time  they  are 
retained  seems  to  vary  a  good  deal  even  in  individuals  of  the  same 
species,  with  the  result  that  some  eggs  when  they  are  laid  contain 
only  the  merest  microscopic  trace  of  the  embryo,  whilst  in  others 
the  young  snakes  may  be  almost  ready  to  hatch.  Snakes,  in  fact, 
C.A.  K 


146  CHILDHOOD  OF  ANIMALS 

seem  to  be  on  the  way  to  protect  the  eggs  by  retaining  them  in 
the  body  until  they  hatch,  and  many  of  them  have  actually  become 
viviparous.  Amongst  these  are  the  smooth  snake,  the  common 
adder,  most  of  the  burrowing  snakes  and  many  of  the  sea  snakes. 
In  viviparous  eggs  the  shell  is  extremely  thin.  It  is  probably  the 
viviparous  habit  that  has  led  to  the  belief  that  the  adder  opens  her 
mouth  and  receives  her  young  into  it  when  danger  comes  near. 
Certainly  the  adder  remains  with  and  protects  her  young  after  they 
are  born,  and  the  sudden  disappearance  of  mother  and  young  when 
any  one  approaches  is  the  starting-point  of  the  notion.  It  has 
been  apparently  confirmed  by  dissection,  for  if  a  gravid  snake  be 
opened,  her  young,  active  and  wriggling,  may  be  found  far  forward 
in  the  body,  in  a  tube  which  is  really  part  of  the  oviduct,  but  which 
one  not  well  acquainted  with  anatomy  might  easily  take  to  belong 
to  the  alimentary  canal.  The  sea  snakes  are  said  to  protect  their 
young  after  hatching,  but  maternal  care  in  most  snakes  does  not  go 
beyond  finding  a  suitable  locality  for  the  eggs,  which  are  usually 
laid  in  heaps  of  earth  and  leaves,  in  holes,  or  in  manure  heaps. 
The  boas  and  pythons  and  some  of  the  venomous  snakes  dispose 
the  coils  of  the  body  round  the  eggs  and  lie  with  them  until  hatching 
takes  place. 

Thus  in  fishes,  batrachians  and  the  different  kinds  of  reptiles, 
there  are  to  be  found  all  stages  in  the  process  by  which  the  number 
of  the  family  is  reduced,  and  better  protection  given  to  the  eggs, 
larvae  and  young.  Prolificness  is  replaced  by  parental  care,  and 
although  there  is  little  or  nothing  that  can  be  thought  of  as  educa- 
tion, the  instincts  of  both  parents  and  young  are  modified  by  the 
association  in  family  life. 


CHAPTER  X 
BROOD-CARE  IN  BIRDS 

ALL  birds  lay  eggs  protected  by  a  hard  shell  and  containing  a 
quantity  of  yolk  for  the  nutrition  of  the  embryo.  The  greater  part 
of  the  development  takes  place  after  the  egg  has  been  laid,  and  is  as 
direct  as  possible,  ancestral  larval  stages  having  been  suppressed. 
The  eggs  themselves  and  the  young  chicks  are  a  tasty  and  nutritious 
prey  for  many  kinds  of  animals.  Some  lizards  and  many  snakes 
are  eaters  of  eggs,  whilst  young  birds  are  even  more  favourite 
victims.  These  reptiles  are  keen-sighted,  active  and  lively,  and 
hunt  over  the  ground,  searching  the  best-concealed  crannies, 
penetrating  dense  thickets  and  climbing  the  tallest  trees.  Nor  do 
birds  themselves  respect  their  own  kind.  In  almost  every  'family 
there  are  some  which  will  prey  on  the  eggs  and  young  of  other 
birds.  Gulls,  magpies,  ravens,  carrion  crows,  moorhens  and  brush 
turkeys  are  notorious  robbers,  and  will  go  long  distances  to  ferret 
out  nests  and  young.  Mammals  of  all  kinds  are  even  more  serious 
enemies,  and  not  a  few  that  are  usually  vegetarian  often  devour 
eggs.  Rodents,  for  instance,  are  habitually  feeders  on  grain,  roots, 
leaves  and  other  vegetable  matter.  But  rats  are  clever  and 
persistent  thieves  of  eggs,  especially  of  those  that  are  to  be  found  on 
the  ground  or  in  holes,  whilst  many  will  ascend  bushes  or  tree 
stumps  in  pursuit  of  their  prey.  Squirrels  have  a  still  greater 
range  of  destructiveness,  as  they  will  hunt  on  the  ground  as  well  as 
on  the  trees,  and  although  for  the  greater  part  of  the  year  they 
are  purely  vegetarian,  in  spring  they  plunder  nests.  The  Zoological 
Society  of  London  introduced  American  grey  squirrels  into  Regent's 
Park,  and  although  these  have  been  a  delight  to  the  people  of  London 
and  have  added  greatly  to  the  pleasure  of  visitors,  it  is  probable 
that  they  have  seriously  diminished  the  bird  population.  Wood- 
pigeons,  thrushes  and  blackbirds  and  all  the  small  songsters  that 
build  in  shrubs  and  hedges  have  had  their  nests  pulled  to  pieces 
and  their  eggs  and  young  destroyed.  The  smaller  tree-climbing 
carnivores,  although  many  of  them  are  vegetarian  and  frugivorous, 

147    •. 


148  CHILDHOOD  OF  ANIMALS 

cannot  refrain  from  eggs,  and  the  fierce  and  bloodthirsty  stoats; 
weasels  and  their  allies  are  relentless  persecutors  of  birds.  Monkeys, 
and  man  himself,  are  still  more  crafty  and  diligent  in  seeking  out  nests. 
I  do  not  know  any  monkey  that  will  refuse  an  egg,  and  even  the 
great  apes,  which  are  amongst  the  most  vegetarian  of  the  Primates, 
greedily  devour  eggs  in  all  stages  of  incubation,  as  well  as  nestlings 
and  young  birds.  The  civilised  boy,  birds '-nesting  in  the  hedge- 
rows, or  scaling  tall  trees  to  add  to  his  collection,  is  pursuing  one  of 
the  oldest  habits  of  his  ancestors. 

It  is  almost  a  wonder  that  any  eggs  hatch  into  nestlings,  any 
nestlings  survive  to  be  fledged,  or  fledglings  reach  the  relative  safety 
of  adult  life.  And  yet  the  eggs  are  so  cunningly  placed,  and  the 
young  so  zealously  guarded,  that  the  limitation  of  the  family  has 
reached  much  further  than  in  the  lower  groups.  The  ostrich,  it  is 
true,  lays  about  thirty  eggs,  but  this  is  an  extreme  instance.  Birds 
such  as  pheasants,  partridges  and  other  ground  birds,  which  fly 
badly  and  are  specially  exposed  to  the  dangers  affecting  the  young 
of  all  birds,  may  lay  as  many  as  twenty  eggs.  Most  of  the  smaller 
arboreal  birds  lay  not  more  than  four  or  five  eggs.  Pigeons, 
birds-of-prey  and  humming-birds  usually  lay  two,  and  many  sea- 
birds  such  as  petrels,  divers  and  guillemots  lay  only  one.  So  also 
most  birds  breed  only  once  a  year,  but,  if  the  first  brood  be  destroyed, 
they  may  lay  a  second  time. 

Brood-care  begins  with  the  selection  of  a  suitable  place  for  the 
deposition  of  the  eggs.  Occasionally  degraded  individuals,  if  we 
take  the  ethical  point  of  view,  or  unusually  intelligent  individuals, 
if  we  take  a  view  more  consonant  with  human  individualism,  will 
make  use  of  the  abandoned  nest  of  other  birds,  or  will  turn  out  the 
occupants  of  an  inhabited  nest,  and  use  it  for  their  own  purposes, 
and  in  some  species  this  has  become  a  habit.  The  cow-birds 
or  American  starlings  (Molobrus)  are  on  the  way  to  lose  the  nest- 
building  instinct  which  they  once  possessed.  The  Argentine 
cow-bird  has  been  seen  by  Mr.  W.  H.  Hudson  trying  to  build,  but 
failing  in  the  effort.  The  females  hang  about  the  nests  of  other 
birds,  particularly  the  mud  houses  of  oven-birds,  and  if  they  find 
one  that  has  been  broken  into,  they  lay  their  eggs  in  it.  When 
nesting-boxes  were  placed  in  trees,  the  cow-birds  were  the  first 
to  visit  them,  inspecting  them  with  mingled  fear  and  curiosity, 
but  finally  using  them.  Other  cow-birds  lay  their  eggs  in  the 
occupied  nests  of  other  birds,  and  as  their  eggs  develop  very  quickly, 
the  young  hatch  out  before  the  legitimate  occupants  and  rob  them 


BROOD-CARE  IN  BIRDS  149 

of  the  parental  care  which  otherwise  they  would  have  enjoyed. 
The  common  cuckoo  and  some  other  cuckoos  carry  this 
parasitic  habit  further.  The  eggs  are  always  deposited  by  the 
female  in  the  nests  of  other  birds,  and  the  young  cuckoo,  when 
it  is  hatched,  creeps  under  the  nestlings  of  its  foster-parents 
and  by  a  violent  effort  raises  them  one  by  one  on  its  hollow  back 
and  jerks  them  out  of  the  nests,  so  securing  undivided  attention 
in  future. 

Some  birds  are  content  with  very  little  preparation  for  the  eggs, 
whilst  in  others  the  most  elaborately  constructed  nests  are  prepared. 
The  New  Zealand  kakapo  or  ground-parrot  hides  in  holes  and  burrows 
and  lays  its  eggs  there  without  any  preparation.  Ostriches  have 
the  reptilian  habit  of  digging  a  hole  in  the  ground,  in  making 
which  several  females  combine,  and  then  deposit  the  eggs  and 
cover  them  up.  Emus  scrape  a  shallow  hole  in  the  ground 
and  do  not  cover  the  eggs.  The  cassowary  scrapes  together  a 
rude  pile  of  leaves  and  mould  on  which  she  lays  the  eggs.  The 
apteryx  lays  a  single  enormous  egg,  which  she  hides  among  fern 
roots.  Most  of  the  auks  lay  their  single  egg  on  a  bare  ledge  of  rock, 
making  no  preparation  for  it.  Penguins  may  lay  on  the  bare  rock 
in  the  huge  communal  rookeries  or  breeding-grounds  which  they 
frequent,  or  may  scrape  together  a  rude  heap  of  debris.  The 
stone-curlew  and  the  goat-sucker  choose  a  site  carefully,  returning 
to  it  year  after  year,  but  make  no  preparation,  laying  the  egg  on 
the  bare  ground.  Birds  -belonging  to  many  different  groups  choose 
natural  cavities,  burrows,  caves,  or  hollow  trees  for  their  eggs,  and 
may  either  line  these  with  leaves,  feathers  and  other  soft  materials, 
or  make  no  further  preparation.  Not  infrequently  they  use  their 
feet  to  enlarge  the  burrows,  or  even  to  dig  them  out.  Puffins, 
for  instance,  regularly  breed  in  rabbits  burrows,  sometimes 
turning  out  the  rabbits,  but  enlarge  them  or  make  shift  to 
dig  holes  for  themselves.  Most  of  the  petrels  and  a  few  ducks 
breed  in  burrows.  The  stockdove  and  the  rockdove  breed  in 
caves,  in  clefts  in  the  rock,  or  in  holes  in  trees.  Most  of  the 
parrots,  as  well  as  kingfishers,  hoopoos,  owls  and  woodpeckers, 
hornbills  and  sand-martins,  dig  out  holes  in  wood  or  sand,  or  occupy 
holes  already  made. 

Most  of  the  game-birds,  shore-birds,  waders,  and  ducks  and 
geese  lay  on  the  ground  or  in  low-lying  situations,  and  show  every 
transition  from  a  mere  scraping  on  the  rocky  shore  to  an  elaborate 
collection  of  twigs,  leaves,  plant  refuse  of  all  kinds,  making  heaps 


150  CHILDHOOD  OF  ANIMALS 

which  may  be  several  feet  high,  whilst  some,  like  the  redshank, 
build  a  dome  of  grass  over  the  eggs.  Floating  nests  on  rafts  of 
water- weeds  or  sticks  are  not  uncommon,  and  there  may  be  little 
attempt  at  choice  of  situation,  or  the  greatest  care  may  be  taken 
in  selecting  a  naturally  concealed  spot.  Some  of  the  mega- 
podes  or  brush  turkeys  bury  their  eggs  in  the  sand,  and  take 
no  further  trouble,  leaving  incubation  to  the  chance  warmth 
of  the  sun.  Others  build  enormous  heaps  of  decaying  leaves, 
the  natural  fermentation  of  which  forms  a  hotbed  in  which 
incubation  takes  place,  without  assistance  from  the  body-heat  of 
the  parents. 

Although  owls  select  holes  in  trees  or  in  caves,  and  line  them  with 
some  warm  material,  the  diurnal  birds-of-prey  select  open  ledges, 
generally  on  inaccessible  cliffs,  and  there  construct  a  very  simple 
nest  of  coarsely  entangled  material.  Twigs  and  dry  branches  are 
collected  and  roughly  intertwined,  and  may  form  a  great  pile  con- 
taining many  hundredweight  of  materials.  The  nest  of  pigeons 
is  a  platform  of  twigs  so  slight  that  the  eggs  are  visible  from  below. 
Crows  and  herons  build  nests  which  show  little  more  skill.  The 
magpie  starts  with  a  similar  rude  platform,  but  may  surround  it 
with  a  hedge  of  thorns,  or  roof  it  over  with  a  dome  of  twigs.  A  pair 
of  hammerkops  or  tufted  umbres  living  in  the  London  Zoological 
Gardens  constructed  a  nest  which  is  a  further  advance  on  that  of 
the  magpie.  They  made  a  platform  of  sticks,  cemented  with  mud, 
and  covered  it  with  a  huge  dome  of  sticks  nearly  two  feet  in  height, 
leaving  a  small  entrance  at  the  side.  Some  of  the  finches,  as,  for 
instance,  the  hawfinch,  begin  with  a  platform  and  then  place  on  it 
a  cup  woven  of  hair  and  rootlets.  Thrushes  make  a  cup  of  rootlets 
and  wool  and  twigs,  supported  on  a  platform  of  twigs,  and  then 
line  it  with  a  plaster  of  mud  and  cow  dung.  In  the  more  elaborate 
nests  of  many  of  the  small  singing  birds,  the  use  of  mud  as  a  cement 
is  discarded  and  the  whole  nest  is  woven  of  the  finest  hairs,  vegetable 
fibres  and  wool,  softened  during  the  process  of  building  by  saliva 
from  the  mouths  of  the  builders.  The  most  curious  and  elaborate 
shapes  may  be  attained,  pendulous  purses,  globes  or  retorts,  or 
hanging  baskets.  There  may  be  one  or  more  entrances,  and  these 
may  be  prolonged  to  form  tubes  or  twisted  tunnels,  possibly  to 
make  access  by  snakes  more  difficult.  The  tailor  birds  select  large 
pendulous  leaves  and  with  their  beaks  pierce  rows  of  holes 
along  the  two  edges  of  the  leaf,  and  then  first  twist  a  thread  out 
of  spiders'  webs,  fragments  of  wool  or  cotton,  and,  weaving  it  in  and 


BROOD-CARE  IN  BIRDS  151 

out  of  the  holes  they  have  made,  bring  the  edges  of  the  leaf  together, 
transforming  it  to  a  hanging  purse,  within  which  the  nest  is  built. 
The  ingenuity  and  diversity  of  the  various  woven  nests  are  endless, 
and  allied  species  show  all  the  stages  between  rude  structures  and 
exquisitely  finished  houses.  There  are  so  many  instances  of  different 
formations  of  the  nest  according  to  the  different  environment  in 
which  the  birds  live,  and  so  many  cases  where  it  seems  plain  that 
the  instinct  is  partly  degenerate,  that  it  is  impossible  to  arrange  a 
parallel  series  between  the  complexity  of  the  nest  and  the  position 
of  a  particular  species  in  its  family.  Types  of  construction  run 
through  the  nests  of  allied  species,  but  appear  in  all  stages  of  per- 
fection and  degeneration. 

Just  as  it  is  impossible  to  draw  a  sharp  line  between  birds  which 
lay  on  the  ground  or  in  holes,  using  no  soft  nesting  material,  or 
little  or  much  of  it,  so  there  are  many  transitions  between  nests  built 
chiefly  of  fibrous  materials,  animal  or  vegetable,  partly  cemented, 
or  lined  or  mixed  with  mud  and  saliva,  and  nests  which  are  formed 
of  mud  or  saliva  almost  wholly.  As,  however,  many  of  the  nests  of 
plastic  material  conform  with  shapes  naturally  suggested  by  fibrous 
substances,  it  is  more  than  probable  that  sticks,  twigs  and  wool  were 
used  and  then  discarded.  So  also  in  the  pursuits  of  man,  rude 
'basket-work  preceded  pottery.  Early  human  workers  found  that 
they  could  improve  their  baskets  by  daubing  them  with  clay,  and 
then  some  made  the  great  discovery  that  clay  alone  was  necessary. 
Early  pottery,  however,  is  often  ornamented  with  patterns  that 
suggest  its  primitive  origin  from  smeared  fibres.  Similarly  there 
are  transitions  between  mud  nests  and  nests  in  holes.  The  hornbill 
selects  a  hollow  tree,  but  the  male  shuts  in  his  mate  with  a  wall  of 
mud.  A  North  American  cliff-swallow  selects  a  hole,  but  builds  a 
rim  of  mud  round  the  aperture.  Swallows  build  their  familiar 
dwellings,  in  corners  under  the  eaves  of  houses,  of  pellets  of  earth 
which  they  collect  and  moisten,  but  mix  with  fragments  of  hay. 
The  Australian  grey  struthidea  makes  a  circular  nest  with  vertical 
walls  wholly  of  mud,  supporting  it  on  the  branch  of  a  tree. 
Flamingoes  build  very  large  conical  mounds  of  mud,  in  the  swamps 
by  the  sea,  and  hollow  a  space  on  the  summit  for  the  reception  of 
the  eggs.  Several  individuals,  probably  a  male  with  two  or  three 
hens,  of  the  South  American  oven-bird  combine  to  build  a  very  large 
oven-shaped  structure.  They  choose  the  branch  of  a  tree  or  the  top 
of  a  post  and  carry  to  it  innumerable  little  pellets  which  they  make 
by  kneading  horsehair  or  rootlets  with  mud  in  a  pool.  They  first 


152  CHILDHOOD  OF  ANIMALS 

construct  a  platform  nearly  a  foot  in  diameter  and  then  gradually, 
layer  by  layer,  rear  up  a  circular  wall  curving  inwards  until  it 
becomes  a  closed  dome  with  an  aperture  at  one  side.  The  aperture 
leads  into  an  outer  chamber,  and  there  is  a  second  inner  chamber 
placed  high  up  and  lined  with  soft  material  for  the  reception  of  the 
eggs.  Some  of  the  swifts  in  Indo-Malay  and  Australia  make 
saucer-shaped  cradles  of  thick  saliva  mixed  with  feathers  and 
fibres,  while  the  swift  from  nests  of  which  "  birds '-nest  soup  "  is 
made  uses  only  saliva. 

When  the  "nest  "  is  merely  a  hole  scraped  in  the  ground,  in  most 
cases  it  is  the  work  of  the  female  only.  When  it  consists  of  a 
quantity  of  material  scraped  up,  or  collected  from  a  distance,  or 
woven  or  moulded  into  a  specially  shaped  receptacle,  both  males 
and  females  join  in  the  task.  There  are  a  good  many  cases  where 
birds  associate  in  colonies  for  nesting.  We  are  all  familiar  with 
rookeries,  and  with  the  massed  nests  of  swallows  and  swifts.  A 
great  many  sea-birds  lay  their  eggs  or  construct  their  simple  nests 
so  close  to  each  other  that  they  almost  touch,  and  there  are  one 
or  two  instances  where  birds  combine  to  form  enormous  structures 
containing  the  individual  nests  of  many  pairs.  It  is  probably 
more  the  common  choice  of  a  suitable  site  than  any  social  instinct 
that  has  led  to  these  associations.  Although  quarrels  and  robberies 
are  frequent,  there  is  a  certain  amount  of  combination  against 
common  enemies,  but  the  families  remain  really  distinct,  and  there 
is  nothing  approaching  the  ordered  communities  that  occur 
amongst  insects. 

When  the  receptacles  are  ready,  the  females  place  the  eggs  in 
them.  Eggs  differ  remarkably  in  shape.  Some  are  almost  spherical, 
most  are  elongated  ovoids  with  one  end  larger  than  the  other,  in 
the  extreme  cases  the  eggs  being  pear-shaped.  Rounded  and 
regularly  ovoid  eggs,  if  given  a  push  on  a  smooth  surface,  will  roll 
a  great  distance  ;  pear-shaped  eggs  simply  twist  round  in  a  circle 
of  which  the  narrow  end  is  the  centre.  Such  eggs  would  certainly 
be  little  liable  to  breakage  by  being  rolled  off  rocky  ledges,  and  they 
are  found  in  the  case  of  many  birds  which  lay  in  dangerous 
situations,  but  they  also  occur  in  shore-birds  where  there  is  no 
similar  danger.  There  appears  to  be  no  advantage  or  special 
adaptation  in  the  various  gradations  from  nearly  spherical  to 
oblong  eggs. 

The  shell  of  eggs  is  a  transparent,  organic  membrane  thickened 
and  hardened  with  deposits  of  lime,  and  the  natural  colour, 


BROOD-CARE  IN  BIRDS  153 

perhaps  the  primitive  colour,  is  white  as  in  the  case  of 
reptiles.  In  a  very  large  number  of  birds  belonging  to  different 
groups  and  with  different  habits  the  white  colour  is  retained. 
Perhaps  the  most  common  case  is  that  of  birds  which  lay  in  holes 
or  in  covered  nests,  and  it  has  been  suggested  that  it  is  an  advantage 
in  such  circumstances,  for  white  is  more  visible  in  dim  light,  and 
therefore  possibly  a  bird  entering  its  dark  nesting-place  might  see 
its  eggs  more  easily  if  they  were  white.  I  cannot  believe,  however, 
that  birds  are  so  stupid  as  to  run  any  great  danger  of  missing  their 
own  eggs.  The  fancy  of  museum  naturalists  has  even  led  them  to 
suppose  that  a  bird  like  the  English  puffin,  which  has  a  coloured 
egg  overlain  by  a  white  chalky  encrustation,  has  only  recently  come 
to  occupy  burrows  in  the  nesting  season,  and  so  has  contrived  to 
cover  up  the  colour  of  its  eggs.  Cormorants,  however,,  nest  on  the 
open  ground  and  similarly  have  eggs  the  pale  blue  or  green  colour 
of  which  is  concealed  by  a  coating  of  chalky  white,  and  Guira 
cuckoos,  which  build  open  nests,  have  pale  blue  eggs  partly  covered 
with  a  network  of  chalk.  Another  explanation  perhaps  errs  in 
attributing  too  much  intelligent  reasoning  to  the  birds.  This 
is  that  many  birds  whose  eggs  happen  to  be  white  take  them 
to  holes  to  hide  them. 

We  are  on  safer  ground  if  we  simply  remember  that  if  the  eggs 
of  birds  were  originally  white,  there  can  at  least  have  been  no 
disadvantage  in  that  colour  being  retained  by  those  which  are  laid 
in  holes  and  other  dark  places.  The  ostrich  buries  its  white  eggs  in 
the  sand.  Bar  bets,  bee-eaters,  hornbills,  jacamars,  kingfishers, 
motmots,  owls,  parrots,  a  few  pigeons,  rollers,  todies,  toucans, 
trogons  and  woodpeckers  all  lay  their  white  eggs  in  holes  in  the 
ground  or  in  the  hollow  branches  of  trees.  But  curassows,  frigate- 
birds,  fiogmouths,  most  herons  and  bitterns,  many  of  the  smaller 
birds- of-prey,  colies,  pelicans,  most  pigeons  and  storks  make  open 
platforms  or  nests  visible  from  above  and  yet  still  lay  white  eggs. 
The  apteryx  has  white  eggs  laid  on  the  ground,  roughly  concealed 
under  foliage.  The  larger  birds-of-prey  have  white  eggs  or  eggs 
blotched  with  red  and  lay  them  in  the  open.  The  eggs  of  ducks, 
geese,  swans  and  flamingoes  are  glossy  white,  or  at  the  most  have  a 
pale  tint  of  yellow  or  blue  ;  many  of  the  game-birds  have  eggs  that 
are  nearly  white,  those  of  grebes  are  white,  although  later  on  they 
become  stained  from  the  wet  moss  and  reeds  of  the  nest,  pelicans 
have  white  eggs,  penguins  have  eggs  that  are  white  or  nearly  white, 
screamers  have  white  eggs,  trumpeters  have  white  eggs,  and  all 


154  CHILDHOOD  OF  ANIMALS 

these  lay  their  eggs  either  actually  on  the  ground  or  on  low  and 
visible  nests. 

The  relation  of  coloured  eggs  to  the  environment  is  even  more 
difficult  to  interpret  as  an  intelligible  adjustment  of  condition  to 
environment.  The  colours  of  eggs  are  all  due  to  pigments  which 
are  derived  from  the  blood  and  find  their  way  to  the  outer  surface 
of  the  eggshell  through  the  walls  of  the  oviduct.  If  a  bird  with 
an  egg  nearly  ready  to  lay  is  frightened  so  that  it  rids  itself  of  its 
burden  before  the  normal  time,  the  premature  egg  is  frequently 
paler,  or  even  colourless,  and  if  more  than  one  egg  is  laid,  it  frequently 
happens  that  those  which  are  deposited  first  are  less  brightly  marked 
or  coloured  than  their  successors.  Many  birds  lay  eggs  which  are 
very  different  in  appearance  from  each  other.  Guillemots  and 
cuckoos  are  well-known  instances  of  this,  and  attempts,  in  my 
opinion  quite  unsatisfactory,  have  been  made  to  show  that  the 
cuckoo  chooses  nests  with  eggs  corresponding  in  colour  to  those 
which  she  has  laid,  as  the  repositories  for  her  own  produce.  Many 
of  the  birds-of-prey,  the  secretary  bird  and  some  petrels,  lay  white 
or  very  pale  eggs  with  irregular  blotches  or  spots  of  red,  the  latter 
in  holes,  the  former  on  rude  heaps  of  twigs  in  the  open.  The  South 
American  ostrich  or  rhea  buries  her  eggs  like  her  African  relative, 
but  they  are  green  or  yellow  at  first  and  afterwards  fade  to  a  dirty 
white.  The  cassowary  and  the  emu  deposit  on  open  nests  eggs 
which  are  evenly  coloured  with  bright  or  dark  green.  Tinamous 
lay,  on  the  bare  ground,  highly  polished  and  lustrous  eggs,  self- 
coloured  with  vivid  shades  which  differ  remarkably  in  the  different 
species,  chocolate,  purple,  blue,  blue-green  or  primrose.  Turacos 
lay  green  eggs  on  an  open  platform,  the  hoopoos  green 
eggs  in  holes,  and  the  bustards  greenish  eggs  with  reddish 
blotches  in  rude  nests  on  the  ground.  Some  ibises  and  spoonbills 
lay  blue  eggs  in  nests  on  trees.  There  is  rather  more  uniformity 
in  the  case  of  spotted  and  blotched  eggs,  which  in  many  cases  are 
laid  on  the  open  ground  and  may  gain  some  protection  from  their 
resemblance  with  pebbles,  a  protection  which  is  most  efficient  in 
shore-birds.  The  latter,  most  of  the  gulls,  coursers,  nightjars, 
cranes  and  button-quails  lay  spotted  or  blotched  eggs  on  the  ground, 
often  with  the  merest  scrape  in  the  sand  to  serve  as  preparation. 
Similar  eggs  are  laid  by  auks  in  holes  or  on  ledges,  by  cariamas  on 
the  ground,  in  bushes  or  on  trees,  by  divers  on  masses  of  grass  and 
herbage  piled  up  near  the  edge  of  the  water,  by  sun-bitterns  on  a 
platform,  and  by  hoatzins  on  tall  trees.  Finally,  amongst  passerine 


BROOD-CARE  IN  BIRDS  155 

birds  almost  every  kind  of  egg,  white,  evenly  tinted  with  some 
bright  colour,  spotted  or  blotched,  is  to  be  found,  and  he  would  be 
ingenious  indeed  who  could  arrange  them  in  a  system  coherent 
with  their  environment. 

The  explanation  of  the  whiteness  of  white  eggs  as  an  adaptation 
to  the  kind  of  places  in  which  such  eggs  are  laid  requires  a  great  deal 
of  bolstering  up  and  stretching  to  make  it  fit  the  facts.  So  also  the 
theories  of  similar  adaptations  in  the  case  of  coloured  eggs  require 
still  more  special  pleading.  Certainly  many  of  the  blotched  eggs 
which  are  laid  on  rocky  ground  or  left  uncovered  amidst  low  herbage 
fit  their  surroundings  extremely  well,  and  may  be  protected  by 
their  invisibility.  But  there  are  other  spotted  and  blotched 
eggs  which  are  laid  in  holes  or  on  inaccessible  ledges,  or  in  covered 
nests,  and  the  explanation  of  protective  resemblance  is  far  from 
complete.  It  seems  almost  impossible  to  imagine  that  there  is 
any  protective  advantage  in  the  brilliantly  coloured  eggs,  those 
with  purple  or  green  or  light  blue  or  burnished  red  hues,  and  to 
add  to  the  difficulty  these  are  laid  in  all  sorts  of  situations,  on  the 
ground,  in  holes,  or  in  covered  or  uncovered  nests.  The  ingenious 
suggestion  has  been  made  that  the  original  egg-eaters  from  snakes 
to  monkeys  became  accustomed  first  to  white  eggs,  as  primitive 
eggs  were  all  white,  and  that  later  on  the  bright  colours  puzzled 
them,  and  made  them  fail  to  recognise  that  such  gaudy  objects  were 
edible.  Hungry  animals,  however,  are  so  experimental,  so  disposed 
to  try  the  taste  of  every  strange  object  that  comes  before  them,  that 
I  do  not  think  this  suggestion  carries  us  very  far.  If  it  were  the 
case  that  brightly  coloured  eggs  were  often  addled,  or  had  nasty 
tastes,  as  happens  with  many  brightly  coloured  insects,  one  might 
believe  that  egg-eaters  after  a  few  experiments  would  give  them  up. 
But  as  any  daring  animal  that  refused  to  be  put  off  by  colour,  or 
any  animal  with  no  natural  appreciation  of  colour,  would  at  once 
discover  that  the  colour  was  only  shell-deep  and  that  the  contents 
were  excellent,  protection  would  soon  come  to  an  end. 

We  have  to  remember,  however,  that  the  existing  colours  and 
patterns  of  eggs  and  of  animals  may  be  survivals  from  circumstances 
in  which  they  were  useful.  Animals,  even  in  recent  times,  have 
spread  from  one  country  to  another,  have  been  driven  or  have 
migrated  from  the  hills  to  the  plains,  from  the  jungle  and  forest  to 
barren,  open  country.  They  have  changed  their  habits  from  choice 
or  from  necessity.  Birds  of  the  same  species  often  nest  under 
different  circumstances  in  very  different  places,  sometimes  in  holes. 


156  CHILDHOOD  OF  ANIMALS 

sometimes  on  the  ground  and  sometimes  on  trees.  Closely  allied 
species  in  many  cases  show  great  differences  in  their  choice  of 
nesting-places  and  in  the  nature  of  the  preparation  they  make. 
Habits  and  surroundings  may  thus  change  very  quickly,  much  more 
quickly  than  we  can  suppose  structure  and  function  to  change, 
and  colours  and  patterns  that  had  fitted  a  former  environment 
may  seem  strange  and  unsuitable  in  a  new  environment.  No  doubt, 
if  they  were  very  unsuitable,  the  old  colours  and  patterns  might 
lead  to  the  extermination  of  their  owners,  before  they  could  be 
changed.  But  equally  possibly  the  advantages  of  the  new  habit 
or  new  surroundings  might  be  so  great  that  they  would  counter- 
balance the  garb  that  had  lost  its  suitability.  Birds  are  a  highly 
successful  branch  of  the  animal  kingdom,  with  great  powers  of 
locomotion  and  with  great  capacities  for  adapting  themselves  to 
new  circumstances,  and  we  might  well  expect  to  find  amongst 
them  many  cases  where  coloration  had  outlived  the  conditions 
to  which  it  was  suited. 

I  hesitate,  therefore,  to  throw  overboard  the  conception  that 
the  coloration  of  the  eggs  of  birds  is  adaptive.  In  many  cases  it 
is  extremely  suitable,  and  there  may  be  other  cases  where  it  was 
recently  suitable.  I  prefer  to  see  in  it,  however,  another  instance 
of  the  change  from  the  plain  to  the  coloured,  from  the  dull  to  the 
gay.  It  is  a  process  not  designed  for  the  pleasure  of  man,  although 
in  many  cases  it  delights  his  eye.  It  is  a  process  which,  so  far 
from  necessarily  being  of  advantage  to  the  animals  in  which  it 
appears,  sometimes  adds  to  their  cares,  but  which  is  occasionally 
neutral  and  now  and  again  of  benefit.  Eggs  were  at  first  white, 
but  there  is  a  tendency  for  them  to  be  stained  with  the  bright  exuda- 
tions of  the  body,  with  the  by-products  of  the  vital  chemistry  of 
the  blood.  Natural  selection,  so  to  say,  has  hung  on  the  outskirts 
of  the  process  of  change,  and  has  retarded  it  where  its  results  were 
dangerous,  and  has  encouraged  it  where  they  were  useful,  and 
where  they  were  indifferent  it  has  left  matters  to  their  natural 
course. 

When  the  eggs  have  been  laid,  they  have  to  be  kept  warm  until 
they  hatch,  a  duty  that  is  avoided  only  in  a  few  rare  cases.  Birds 
are  even  more  hot-blooded  than  mammals  ;  it  is  not  always  easy  to 
take  their  temperature  accurately,  as  the  act  of  handling  them 
excites  them  and  raises  the  temperature,  but  it  seems  to  range 
from  the  human  normal  to  about  104°  or  105°  Fahr.  The  eggs 
must  be  kept  at  temperatures  approaching  or  surpassing  these 


BROOD-CARE  IN  BIRDS  157 

for  the  whole  period  of  incubation,  although  cooling  for  a  short 
time,  such  as  happens  when  the  brooding  bird  leaves  the  nest  to 
feed,  does  no  harm,  and  is  even  imitated  by  those  who  are  most 
successful  in  using  artificial  incubators.  The  time  required  varies 
from  about  ten  days  (in  some  of  the  small  singing  birds)  to  about 
six  weeks  or  two  months  (ostrich).  On  the  whole  it  is  rather 
shorter  in  small  birds  than  in  large  birds,  at  least  within  the  same 
families.  Thus  the  small  ducks  require  about  three  weeks,  geese 
about  a  month  and  swans  about  forty  days.  Comparing  groups 
with  groups,  there  is  much  difference  which  is  not  easy  to  explain, 
but  the  most  general  arrangement  is  that  when  the  eggs  are  small, 
containing  little  food-yolk,  and  the  young  are  hatched  in  an  im- 
perfect condition,  the  period  of  incubation  is  short,  as,  for  instance, 
amongst  passerine  birds,  and  where  the  eggs  are  relatively  large, 
containing  much  food -yolk,  and  the  young  are  hatched  in  a  more 
advanced  state  of  development,  the  period  occupied  is  longer. 

All  the  megapodes  or  brush  turkeys  have  given  up  brooding  the 
eggs.  Some  of  them  lay  in  the  warm  sand,  others  are  said  to  select 
the  neighbourhood  of  hot  springs,  whilst  others  again,  like  the 
brush  turkey  most  familiar  in  captivity,  make  huge  mounds  of 
vegetable  matter,  the  fermentation  of  which  supplies  the  necessary 
heat.  The  cuckoos  in  the  Old  World,  and  the  cow-birds  in  the  New 
World,  foist  their  eggs  on  other  birds  for  incubation  as  well  as  for 
subsequent  feeding,  and  not  a  few  of  the  owls  are  suspected  of  the 
same  habit. 

In  some  cases  the  male  bird  performs  the  whole  duty  of  incubation. 
This  happens  in  the  cassowary,  rhea,  tinamous,  phalaropes  and 
painted  snipe,  and  it  is  amongst  these  that  the  curious  cases  occur 
in  which  the  males  are  more  dully  coloured  than  the  females.  In 
many  birds  both  sexes  share  the  duty.  The  cock  ostrich  watches 
over  the  hole  in  which  the  eggs  have  been  buried,  by  night,  whilst 
the  hen  takes  up  the  duty  by  day.  The  screamers  work  in  shifts 
of  two  or  three  hours  each.  When  they  bred  in  the  London 
Zoological  Gardens,  it  was  noticed  that  the  cock  bird  acted  as  time- 
keeper, and  at  the  end  of  a  watch  used  to  come  and  push  the  female 
off  the  nest.  The  emperor  and  king  penguins  lay  their  single  eggs 
on  the  bare  ground,  often  in  extremely  inclement  weather  when 
there  are  heavy  storms  of  snow  and  severe  frost.  Each  egg  is 
brooded  on  the  flat  feet  of  the  bird,  and  a  warm  flap  of  skin  and 
feathers,  specially  enlarged  during  the  breeding  season,  hangs 
down  from  the  abdomen  and  covers  it  like  a  blanket.  From  time 


158  CHILDHOOD  OF  ANIMALS 

to  time  the  male  and  female  relieve  one  another,  and  this  is  done 
with  a  quaint  ceremony  of  bowing,  and  with  a  careful  scrutiny  of 
the  egg  before  it  is  handed  over.  Large  numbers  of  eggs  are 
destroyed  by  the  weather,  and  so  great  is  the  desire  of  these  birds 
to  brood  that  they  will  steal  an  egg  for  this  purpose.  Probably  the 
eggs  are  changed  so  often  that  family  rearing  has  been  replaced  by 
communism.  In  the  sand-grouse  and  the  bustards  both  parents 
share  in  incubation,  but  in  the  great  majority  of  the  higher  types 
the  female  alone  does  the  work. 

When  the  female  only  broods  over  the  eggs,  the  male  may  take 
no  interest  in  the  proceedings,  or  may  remain  as  a  guardian  of  the 
nest  and  hen,  or  may  assiduously  feed  her.  As  soon  as  the  female 
duck  begins  to  sit,  the  drake  flies  off  and  does  not  reappear  until 
the  young  are  nearly  fledged.  In  gulls,  most  of  the  birds-of-prey, 
swans,  storks  and  rails  the  male  keeps  near  the  nest,  and  savagely 
attacks  any  intruders.  In  Montagu's  harrier  and  some  other  birds- 
of-prey,  the  cock  brings  food  to  the  hen,  whilst  it  is  almost  the  rule 
amongst  singing  birds  for  the  male  to  remain  with  the  female  and 
assist  in  feeding  her.  The  hornbill,  which  walls  up  the  female  in 
the  trunk  of  a  tree  during  the  breeding  season,  feeds  her  most 
diligently,  and  indeed  she  would  otherwise  starve. 

All  birds  during  incubation  take  a  great  deal  of  trouble  with  the 
eggs,  often  turning  and  rearranging  them,  sometimes  covering  them 
up  when  they  leave  them,  and  often  bringing  fresh  material  to  add 
to  the  nest.  It  is  quite  certain  that  sometimes  because  they  have 
been  disturbed,  possibly  when  some  of  the  eggs  have  been  taken, 
and  sometimes  for  no  apparent  reason,  they  get  dissatisfied  with 
the  nest,  become  suspicious  and  desert  it.  If  a  nest  be  disturbed 
before  its  construction  is  completed,  the  birds  generally  leave 
it  and  begin  a  new  one  somewhere  near.  In  zoological  gardens, 
building  birds  are  very  capricious  in  this  matter  and  will  frequently 
pull  a  nest  to  pieces  and  begin  a  new  one,  or  desert  the  old  one 
entirely.  When  the  eggs  have  been  laid,  what  usually  happens, 
if  a  disturbance  has  taken  place,  is  that  the  nest  is  deserted,  and  if 
it  is  sufficiently  early  in  the  season,  a  new  set  of  eggs  is  laid  in  the 
new  nest.  Even  when  the  young  have  been  hatched,  desertion  is 
the  usual  result  when  the  parent  has  been  disturbed  or  annoyed. 
In  similar  cases  amongst  mammals,  the  mothers,  even  although 
they  are  not  naturally  carnivorous,  will  kill  and  eat  their  own 
young. 

Brood-care  of  another  kind  begins  when  the  eggs  hatch  out,  and 


BROOD-CARE  IN  BIRDS  159 

its  nature  depends  partly  on  the  condition  of  the  young  chicks. 
There  can  be  no  doubt  but  that  birds  are  modified  reptiles,  and 
most  probably  ancestral  birds,  like  living  reptiles,  hatched  out  in  a 
condition  in  which  they  were  active  and  very  closely  resembled 
their  parents.  If  they  were  unable  actually  to  fly,  they  at  least 
could  run  about  actively,  and  make  fluttering  or  gliding  and  para- 
chute-like motions  with  their  wings.  The  megapodes  are  the  only 
living  birds  that  are  hatched  in  such  a  stage  that  they  are  able  to 
fly  at  once,  and  in  which  parental  care  ceases  with  the  laying  of  the 
eggs  in  a  suitable  place.  It  is  improbable,  however,  that  these 
represent  an  actually  primitive  condition  that  has  survived. 
They  pass  through  a  moult  before  they  are  hatched  and  it  is  very 
likely  that  their  extreme  precocity  is  a  comparatively  recent 
acquisition.  If  we  count,  not  by  species,  but  by  orders,  sub-orders 
and  really  well-separated  families,  then  by  far  the  greatest  number 
of  different  kinds  of  birds  are  hatched  in  a  stage  in  which,  although 
they  are  not  able  to  fly,  they  are  alert,  active,  able  to  see  and  to 
pick  up  their  own  food,  and  all  these  are  clad  from  the  first  in  a  coat 
of  down.  Lists  of  names  are  not  usually  interesting,  but  I  am 
going  to  give  a  rough  list  which,  although  not  complete,  will  carry 
conviction.  The  young  of  the  following  groups  are  active  and 
downy,  or  precocious  when  they  are  hatched :  Auks,  bustards, 
cariamas,  cassowaries,  coursers,  cranes,  curassows,  divers,  ducks, 
geese  and  swans,  emus,  flamingoes,  frigate-birds,  frog-mouths, 
game-birds  (including  pheasants  and  fowls,  peacocks,  partridges, 
quail  and  all  their  allies),  grebes,  gulls,  hemipodes,  hoatzins,  jaca- 
mars,  kiwis,  nightjars,  ostriches,  penguins  (although  these  are 
rather  helpless),  rails,  rheas,  sand-grouse,  screamers,  seedsnipes, 
sheathbills,  shore-birds,  (including  all  the  plovers,  turnstones, 
woodcock,  snipe,  avocets,  oyster-catchers,  sand-pipers,  and  their 
immediate  allies),  tinamous,  turacos  and  trumpeters.  This  list 
plainly  includes  birds  of  very  different  types  with  very  different 
habits,  but  I  think  I  can  make  the  general  statement  about  it  that 
it  does  not  include  the  higher  types  of  birds  and  notably  the  perching 
and  singing  birds. 

Next,  there  is  a  smaller  assemblage  of  birds,  to  which  the  penguins 
in  the  first  list  form  a  halfway  stage.  In  these  the  young  are 
helpless  when  they  are  hatched,  but  are  covered  with  a  coat  of 
down.  Such  are  the  American  vultures,  all  the  ordinary  birds-of- 
prey,  the  eagles,  hawks,  harriers  and  Old  World  vultures,  herons  and 
bitterns  (although  in  the  latter  the  coat  of  down  is  thin  and  hairy), 


160  CHILDHOOD  OF  ANIMALS 

ibises  and  spoonbills,  lyre-birds,  owls,  petrels,  pigeons  (in  these 
again  the  down  is  so  scanty  as  almost  to  be  absent),  the  secretary 
bird,  storks,  sun-bitterns  and  tropic  birds.  Most  of  these  are 
rather  large  or  powerful  and  ferocious  birds,  well  able  to  defend 
their  young.  Lastly  there  is  a  group  in  which  the  young  are 
hatched  naked  and  helpless.  The  pigeons  and  herons  almost 
might  be  placed  here,  and  the  group  includes  some  like  gannets, 
cormorants,  and  pelicans  and  parrots,  in  which  down  is  very  soon 
developed,  and  many  in  which  there  are  slight  traces  of  down,  but 
on  the  whole  they  are  practically  downless.  This  third  list  contains 
barbets,  bee-eaters,  cormorants  and  gannets,  cuckoos,  honey-guides, 
lioopoos,  hornbills,  humming-birds,  kingfishers,  motmots,  colies, 
parrots,  passerine  birds,  pelicans,  rollers,  swifts,  todies,  toucans, 
trogons,  woodpeckers.  The  most  general  statement  to  be  made 
about  this  last  list  is  that  it  contains  those  birds  which  most 
anatomists  would  recognise  as  being  the  highest  or  most  bird-like 
birds. 

There  has  taken  place  amongst  birds,  or  rather  I  might  say  there 
is  taking  place  amongst  birds,  a  change  from  a  condition  in  which 
the  newly  hatched  young  can  very  quickly  look  after  themselves, 
to  a  condition  in  which  the  young  are  absolutely  dependent  on  their 
parents  for  some  time  after  they  are  hatched.  The  older,  more 
reptilian  condition  in  which  the  young  were  provided  for  by  a 
merely  material  sacrifice  on  the  part  of  the  mother,  by  storing  a 
large  quantity  of  yolk  in  the  egg,  is  being  replaced  by  a  condition 
in  which  the  self-seeking  instincts  of  the  parents  are  temporarily 
changed  into  instincts  and  habits  where  the  main  object  of  life  is 
not  self-interest,  but  the  satisfying  of  the  needs  of  others. 

Even  when  the  newly  hatched  young  are  fairly  active  and  soon 
able  to  feed  themselves,  one  or  both  parents  guard  and  protect 
them  for  a  considerable  time.  They  exchange  call-notes  and  when 
danger  comes  near,  the  young  hasten  to  shelter  under  the  wings 
of  their  parent  or  sqtfat  down  whilst  she  attempts  to  lure  away  the 
intruder,  sometimes,  like  the  plover  or  the  partridge,  pretending  to 
have  a  broken  limb  or  to  be  lame,  and  so  diverting  attention  to  her- 
self, sometimes,  as  in  the  case  of  the  hens  of  fowls  and  pheasants,  or 
by  the  cocks  and  hens  in  gulls,  attacking  the  supposed  enemy  savagely. 
A  few  birds  carry  their  young  about.  The  woodcock  holds  them 
between  her  legs,  partly  supporting  them  by  her  beak  when  she 
flies  from  one  feeding-ground  to  another.  Grebes  carry  the  young 
on  the  back  as  they  swim  through  the  water,  and  every  one  must 


BROOD-CARE  IN  BIRDS  161 

have  seen  cygnets  taking  refuge  on  the  back  of  the  male  or  female 
swan,  nestling  under  their  wings  as  they  swim  (see  Plate  XI,  p.  240). 

When  the  young  are  helpless,  the  parental  care  and  protection 
are  even  greater.  Birds  which  are  naturally  timid  will  fly  out  and 
strike  savagely  at  disturbers  of  their  nests  and  young,  whilst  those 
that  are  strong  and  predatory  are  extremely  dangerous  to  approach, 
when  they  are  with  eggs  and  young.  Most  of  them  take  great  trouble 
with  the  sanitation  of  the  nest  or  of  the  breeding-hole,  first  them- 
selves carrying  away  the  droppings  of  the  young  birds,  and  after- 
wards encouraging  the  nestlings  to  void  their  excretions  over  the 
edge  of  the  nest.  There  are  a  few  birds,  such  as  hoopoos  and 
kingfishers,  which  take  no  trouble  in  these  matters,  but  the  nests  and 
the  bodies  of  most  young  birds  are  kept  scrupulously  clean. 

Finally,  in  all  cases  where  the  young  are  helpless,  and  in  a  good 
many  where  they  are  active,  one  or  both  parents  work  assiduously 
in  feeding  them.  Whatever  be  the  natural  diet  of  the  adults,  the 
food  of  the  young  is  almost  always  animal  matter.  There  are  of 
course  some  exceptions.  Ostriches,  almost  as  soon  as  they  are 
hatched,  begin  to  crop  green  herbage  for  themselves,  although 
cassowaries,  emus  and  rheas  require  food  such  as  insects  and  spiders. 
The  secret  of  rearing  ducklings  of  almost  every  kind  is  to  supply 
them  abundantly  with  the  common  duckweed  of  ponds,  and  although 
there  is  usually  a  rich  microscopic  animal  life  adherent  to  these 
plants,  the  bulk  of  the  food  is  vegetable.  But  all  the  soft-billed 
birds,  which  are  naturally  insectivorous,  most  of  the  fruit-eaters 
and  practically  all  the  hard-billed  seed-eaters  work  from  dawn  to 
dark  searching  for  grubs,  caterpillars,  maggots,  worms  and  all 
manner  of  creeping  and  flying  things. to  feed  their  hungry  young. 
Other  birds  hawk  insects  on  the  wing  for  the  same  purpose,  and  those 
who  resent  the  occasional  devastations  of  their  fruit-gardens  and 
seed-beds  should  remember  that  human  life  would  be  almost  in- 
tolerable, and  the  toil  of  the  gardener  and  farmer  almost  futile, 
were  it  not  for  the  destruction  of  insects  and  their  larvae  which  is 
the  work  of  birds  engaged  in  feeding  their  young. 

Many  birds  feed  their  young  on  food  which  they  have  partly 
digested  and  throw  up.  Some  of  the  finches,  which  at  first  bring 
insects  to  their  young,  afterwards  feed  them  on  partly  digested 
food.  Parrots  also  digest  their  vegetable  food  and  supply  it  to  the 
young  in  this  condition,  whilst  some  woodpeckers,  martins  and 
others  throw  up  digested  insects.  Storks  break  up  frogs,  worms, 
pieces  of  fish  or  flesh,  mix  it  with  partly  digested  matter  and  throw  it 

C.A.  L 


162  CHILDHOOD  OF  ANIMALS 

on  the  edge  of  the  nest  for  their  young.  The  adult  gull  on  Plate  VIII 
was  drawn  in  the  attitude  assumed  just  before  she  throws  up  food 
for  the  young.  Petrels  secrete  a  kind  of  oil  from  the  fish  on  which 
they  live,  and  discharge  it  by  their  beaks  into  the  mouths  of  their 
young.  Little  cormorants  thrust  their  bills  down  the  short  straight 
throat  of  their  mothers  and  help  themselves  from  her  stomach  ; 
whilst  young  pel  cans  take  fish  from  the  mother's  enormous  pouch- 
like  bill.  Young  pigeons  obtain  their  food  by  thrusting  their 
beaks  into  the  mouth  of  the  mother  and  absorbing  the  so-called 
pigeons'  milk,  which  is  partly  digested  food  and  partly  a  secretion 
from  the  crop.  Whatever  method  be  adopted,  the  feeding  of  the 
young  may  go  on  until  these  are  nearly  as  large  as  the  parents. 

Young  birds,  especially  those  that  are  born  naked,  are  extremely 
sensitive  to  cold,  their  temperature  rising  and  falling  with  that  of 
the  surrounding  air,  just  as  happens  with  reptiles,  and  no  small 
part  of  the  duty  of  the  parents  is  to  keep  them  warm.  This  is 
generally  the  work  of  the  mother,  and  for  some  days,  in  the  case  of 
the  smaller  singing  birds,  she  hardly  leaves  the  nest,  the  male 
during  this  time  doing  all  the  work  of  foraging.  In  four  or  five 
days  the  little  birds  have  found  their  feet  and  are  able  to  move 
about  in  the  nest,  and  then  the  mother  is  able  to  leave  them  for  a 
longer  interval,  and  to  take  up  her  share  of  collecting  food. 

And  so  in  nearly  all  birds,  from  the  choice  of  the  place  for  the 
eggs,  through  the  long  duty  of  incubation,  and  for  a  longer  or  shorter 
period  after  the  young  are  hatched,  one  or  both  of  the  parents 
are  fully  occupied  with  parental  duties.  The  final  period  of  brood- 
care  lasts  for  periods  varying  from  three  weeks  to  several  months. 
Then  suddenly  it  comes  to  an  end.  The  parents  resume  their 
natural  devotion  to  their  own  personal  wants,  and  even  those  that 
have  been  most  assiduous  and  most  devoted  now  quite  suddenly 
either  fly  off  to  new  haunts,  leaving  their  offspring  behind,  or  drive 
the  fledglings  away  from  them.  The  abandoned  young  often 
consort  until  they  have  reached  sexual  maturity,  when  new  instincts 
awaken  and  the  battles  for  mates  begin. 

If  the  time  occupied  in  building  the  nest,  in  incubation  and  in 
looking  after  the  young  be  added,  and  if  it  be  remembered  that 
most  birds  breed  at  least  once  a  year,  and  those  which  get  over 
their  duties  quickly  often  breed  twice  a  year,  we  reach  the  conclusion 
that  a  large  part  of  the  time  of  adult  birds  is  occupied  with  parental 
care.  This  increased  care  has  made  it  possible  for  the  number  in 
the  family  to  be  very  greatly  diminished. 


PLATE  VIII 

SEA-GULLS  AND  YOUNG 

In  the  foreground  are  newly  hatched  young  gulls  in  spotted 
downy  plumage.  Above  them,  and  in  the  attitude  assumed 
just  before  throwing  up  food  for  the  young,  is  a  great  Black- 
backed  Gull  in  the  full  black-and-white  plumage  of  the 
adult.  Above  that  is  a  gull  in  the  "plumage  before  the 
final  stage  ;  there  are  still  spots  on  the  head  and  much 
brown  on  the  wings.  The  bird  highest  up  on  the  plate 
is  in  an  early  immature  plumage,  still  completely  spotted 
and  mottled. 


The  ad-  ite  VIII 

;  just  b<  up  food 

i  kind  of  oil  frc  hich 

>y  their  beaks  into  the 
arust  their  bills  down  the  short  straight 
and  help  themselves  frorr 

from  the  motht 

)ns   obtain    their  food   by  thrusting  their 
••'»  oi     he  mother  and  absorbing  the  so-called 
i:         :ly  digested  food  and  partly  u  secretion 
.    .       method  be  adopted,  the  feeding  of 
i]  uly  as  large  as  the  parents. 

;pecialJ      1!  ?q     born  naked,  are  extrer; 

()..  II  that  ( 

o  small 

i>ottoq«  fii  i    This  is 

bomjjr  »i  'jilt  fit  i  "Q&ck  ro« 

-A-jBlB 
irft-  \o 

rti  ttttg-k  ^i  iB«#  ovod/ 
oil!  uo  cJtoqa:  iic*«  &-i  ;  ^pgeafehd  to  ir; 


d4n^ffl:  {  em  for  a 

tmtoq.  ^btaftmoo 


Is,  irom  the  choice  of  the  place  for 
of  incubation,  and  for  a  longer  or  sh- 

atched,  one  or  both  of  the  parents 
parental  duties.  -  The  final  period  of  brood- 
,g  from  three  weeks  to  several  months. 
o  an  end.    The  parents  resume  their 
nal  wants,  and  even  those  that 
ind  most  devoted  now  quite  suddenly 
ving  their  offspi  ad,  or  drive 

m.     The    abandoned    young    c 
lal  maturity,  when  new  insi 
iates  begin. 
;  uilding  the  nes 
added,  and  if  it  1 

a  year,  and  which  get  < 

twice  a  year,  we  reach  the  cond 
idult  birds  is  occupied  with  pa 
je  it  possibi  :e  numl 


• 


'•**•> 


CHAPTER  XI 
BROOD-CARE  AMONG  MAMMALS 

MAMMALS  are  not  only  the  highest  group  of  the  animal  kingdom, 
but  one  of  the  latest  products  of  evolution.  At  a  time  which  is  not 
very  remote  in  geological  history,  a  set  of  reptiles  slowly  assumed 
the  mammalian  characters,  and  there  is  no  reason  to  doubt  but  that 
these  ancestral  reptilian -mammals  laid  large  eggs  like  living  reptiles. 
Some  of  the  living  reptiles,  like  some  living  fishes,  retain  the  eggs 
in  the  body  until  they  are  almost  ready  to  hatch,  and  so  secure 
for  them  warmth  and  protection  much  more  certainly  than  in 
the  most  cunningly  devised  nest.  Some  reptiles  even  keep  the 
eggs  in  the  body  until  they  hatch.  It  is  most  easy  to  understand 
what  now  happens  in  mammals  if  we  suppose  that  their  reptilian 
ancestors  had  acquired  this  habit  of  egg  retention.  The  lowest 
living  mammals,  the  duck-billed  mole  and  the  spiny  anteater  of 
Australia,  still  lay  rather  large  eggs,  but  retain  them  in  the  body  until 
they  are  nearly  ready  to  hatch.  The  marsupials  and  all  the  higher 
mammals  not  only  retain  the  eggs  in  the  body  but  change  the  way  of 
feeding  the  embryo  in  a  fashion  that  is  foreshadowed  even  in  some 
fishes.  In  ordinary  large  eggs  which  contain  enough  food  stored  up 
as  yolk  to  nourish  the  young  until  it  is  hatched,  the  blood-vessels 
of  the  growing  embryo  spread  out  over  the  yolk  just  under  the 
eggshell  and  absorb  oxygen  from  the  air  through  the  shell  as  well 
as  food  from  the  yolk  inside  the  shell.  When  such  an  egg  lies  in 
contact  with  the  wall  of  the  egg-duct  of  the  mother,  the  supply 
of  oxygen  for  the  embryo  must  be  picked  up  from  the  blood  of  the 
mother.  This  has  led  to  two  changes.  In  the  first  place,  the  embryo 
picks  up  from  the  blood  of  the  mother  not  only  oxygen  but  the  food 
it  requires,  so  that  the  yolk  is  no  longer  necessary  ;  and  in  the  second 
place  the  eggshell  becomes  thin,  soft  and  membranous  so  that  the 
connection  between  the  blood  of  the  mother  and  of  the  embryo 
becomes  closer.  Most  of  the  marsupials  have  remained  in  this  stage. 
They  have  eggs  that  are  smaller  in  proportion  than  those  of  reptiles 
or  than  those  of  the  lowest  mammals,  but  much  larger  and  containing 

163 


164  CHILDHOOD  OF  ANIMALS 

more  food  than  those  of  the  higher  mammals.  In  the  latter  there  is 
practically  no  food-yolk  at  all,  and  the  eggs  are  microscopic  in  size, 
being  just  visible  to  the  naked  eye.  They  soon  develop  a  connection 
with  the  maternal  tissues  which  is  a  legacy  from  the  blood-vessels 
which  spread  out  under  the  shell,  and  then  replace  that  by  a 
new  and  more  perfect  means  of  drawing  nutriment  from  the  blood 
of  the  mother,  the  structure  which  is  known  as  the  placenta. 

In  mammals,  therefore,  the  earliest  stages  of  brood-care,  instead 
of  being  apparently  conscious,  external  acts,  which,  so  to  say,  might 
be  slurred  over,  bungled  or  forgotten,  have  become  a  part  of  the  un- 
conscious mechanism  of  the  body.  Instead  of  having  to  construct  a 
safe  place  in  which  to  lay  eggs,  the  mother  retains  them  in  the  interior 
of  her  body,  supplies  them  with  the  necessary  warmth  and  food,  and 
protects  them  from  enemies  at  the  peril  of  her  own  life.  This  change 
from  external  to  internal  protection  is  least  complete  in  the  egg- 
laying  mammals,  more  complete  in  the  kangaroos  (where  the  young 
are  born  when  they  are  very  small  and  placed  in  an  external  pouch 
by  the  mother),  and  most  complete  in  the  higher  mammals.  Just 
as  there  are  some  birds  hatched  when  they  are  ready  to  run  about 
and  others  hatched  when  they  are  still  blind  and  feeble,  so  there  are 
some  mammals  where  the  young  are  born  almost  ready  to  walk  or 
to  run,  and  others  where  they  are  born  blind  and  naked,  differences 
which  depend  on  the  habits  of  the  animals  and  may  be  found  amongst 
species  that  are  very  closely  allied. 

This  internal  organic  brood-care  is  just  as  effective  in  protecting 
the  young  as  the  brooding  of  birds,  and  it  is  followed  by  a  still 
longer  period  in  which  the  new-born  mammals  are  fed  and  guarded 
by  the  mother.  And  so  it  happens  that  amongst  mammals  brood- 
care  is  more  elaborate  and  complete  than  in  any  of  the  other  groups 
of  the  animal  kingdom.  The  young  do  not  leave  their  parents  until 
they  are  well  equipped  to  fight  the  battle  of  life  for  themselves. 
The  maintenance  of  the  species  by  the  production  of  enormous 
families  has  ceased.  Some  of  the  little  rodents  may  breed  several 
times  in  the  course  of  the  year  and  produce  rather  large  litters,  and 
there  are  some  fecund  mammals,  such  ,as  pigs,  where  the  litter  may 
contain  a  dozen  or  even  more.  But  these  are  rare  exceptions.  In 
the  vast  majority  of  cases,  mammals  breed  no  more  than  once  a 
year,  and  in  some  instances  only  once  in  every  two  or  three  years. 
The  usual  numbers  are  one,  two  or  three  at  a  birth,  and  the  higher 
in  the  scale  of  mammalian  life  one  looks,  the  smaller  is  the  number 
that  is  usual. 


PLATE  IX 

FEMALE  CAPPED  LANGUR  MONKEY 
AND  YOUNG 

The  drawing  shows  in  two  positions  a  mother  and  her  baby 

a  few  days  after  the  young  one  was  born  in  the  London 

Zoological  Gardens. 


164 


CHIlDHOOl 


more  food  than  those  of 
ly  no  food -yolk 


more 

orn  \\ 

and  others 
mam 

to  run,  am 
which  depc 


the  young  ;> 


frc 


o 


ffi  ' 


shell,  and  then  replace  that  by  a 
drawing  nutriment  from  the  blood 
which  is  known  as  the  p 

st  stages  of  brood-care,  insi 
iial  acts,  which,  so  to  say,  might 
.  have  become  a  part  of  the  tln- 
e  bod  of  having  to  construct  a 

^d  food,  and 
This  ch 

tt3<lW3  .TTAIATT 

i  about 

JA  ble,  so  there  are 

ing  are  born  almost  ready  to  walk  or 

.  ;  e  born  blind  and  naked,  differences 

animals  and  may  be  found  amongst 


re  is  just  as  effective  in  prote 

I  of   birds,  and  it  is  followed  by  a  still 

>orn  mammals  are  fed  and  gun 

that  amongst  mammals  brood- 
complete  than  in  any  of  the  other  gr 
'he  young  do  not  Barents 

life  for  th. 
s  by  t! 
little  roc 
produce  rar  • 
ch.as  p, 
But  th 

t)reed  no  more  than  or 

iiex  small  number 


i 


BROOD-CARE  AMONG  MAMMALS  165 

The  preparation  for  the  birth  of  the  young  is  seldom  a  serious 
matter  amongst  mammals.  Those  which  have  not  natural  homes, 
and  a  good  many  of  the  others,  do  not  seem  to  be  aware  of  the 
approaching  event  almost  until  the  actual  birth  begins,  and  merely 
follow  the  natural  instinct  of  animals  that  do  not  feel  quite  well. 
They  retire  from  their  companions  and  seek  a  sheltered  place. 
Nothing  is  known  as  to  birth  in  the  case  of  the  man-like  apes  in  the 
wild  state,  and  I  do  not  know  of  any  instance  where  they  have  bred 
in  captivity.  Baboons,  cercopitheques,  langurs,  macaques  and  many 
of  the  small  American  monkeys  have  bred  in  captivity.  The 
female  which  is  about  to  be  a  mother  generally  shows  an  enlarge- 
ment of  the  breasts  and  a  slight  restlessness  for  a  day  or  two  before 
the  actual  birth  ;  sometimes  she  ceases  to  take  food  and  retires  into 
her  shelter  or  sleeping-box,  to  appear  again  with  her  infant.  The 
capped  langur  monkey  which  is  shown  with  her  baby  in  two 
positions  on  the  plate  (IX)  seemed  to  have  been  as  much  taken  by 
surprise  as  her  keeper  in  the  London  Zoological  Gardens.  The  birth 
took  place  at  night,  and  the  mother,  from  the  marks  in  the  cage, 
must  have  dragged  about  the  astonishing  object  she  found  until  the 
placenta  got  broken  off.  By  morning,  however,  she  had  grown  accus- 
tomed to  the  baby  and  carried  it  pressed  against  her  breast,  from 
time  to  time  thrusting  the  head  outwards  and  eagerly  looking  at  it. 
The  baby  clung  tightly  to  the  mother  with  both  its  arms  round  her, 
and  its  long  tail  hanging  down.  When  the  mother  leapt  about  her 
cage,  or  went  to  the  outdoor  compartment,  the  baby  itself  clung 
to  her.  It  was  only  when  the  mother  was  at  rest  that  she  supported 
it  with  her  arms.  For  several  weeks  the  baby  never  left  her 
and  she  showed  endless  curiosity  and  pleasure  in  it,  ceaselessly 
examining  it,  turning  it  over,  stroking  it  and  keeping  it  clean  with 
her  hands.  She  was  jealous  of  visitors,  and,  when  they  approached, 
she  used  to  turn  round  so  as  to  hide  the  baby  from  them.  The 
father,  in  case  of  accident,  had  been  taken  away  and  put  in  the 
adjoining  cage,  which  was  shut  off  by  a  piece  of  canvas.  He  made  a 
hole  in  this,  and  from  time  to  time,  especially  when  the  mother  or 
baby  made  any  noise,  he  would  raise  the  torn  flap  and  peep  through. 
In  about  a  month  the  baby  sometimes  left  the  mother,  but  rushed 
back  to  her  at  the  slightest  sign  of  danger.  Apart  from  feeding  it 
at  the  breast,  this  mother,  like  all  other  monkeys  I  have  ever  seen, 
made  no  attempt  to  give  its  young  food  or  to  share  food  with  it.  A 
Japanese  ape  born  in  the  London  Zoological  Gardens  grew  up  with  its 
father  and  mother.  When  it  was  quite  young  the  mother  and  young 


166  CHILDHOOD  OF  ANIMALS 

behaved  in  exactly  the  same  way  as  the  langur  and  her  baby,  and 
the  father  took  a  lively  interest  in  his  child,  but  did  not  share  in 
protecting  it  in  any  way.  Later  on,  when  the  young  ape  began  to 
take  food  itself,  the  parents  did  not  scramble  with  it  for  dainties, 
in  the  usual  fashion  of  monkeys  living  together,  but  they  showed  no 
signs  of  sharing  food.  Marmosets  breed  quite  often  in  captivity, 
the  birth  usually  taking  place  in  the  sleeping-box.  They  often 
show  a  perverted  instinct  which  is  not  infrequent  amongst 
mammals,  but  very  rare  in  the  case  of  monkeys.  In  the  first  day 
or  two  the  mother  may  kill  and  eat  her  young.  In  the  carni- 
vores this  perhaps  is  not  so  surprising.  When  the  cubs  are  feeble, 
or  die  from  natural  causes,  it  would  not  be  unnatural  for  a  carnivorous 
mother  to  eat  them,  and  it  happens  more  often  with  young  and 
inexperienced  mothers  who  neglect  their  young.  But  it  also  occurs 
in  the  case  of  many  animals  that  are  not  carnivorous,  where  the 
conditions  are  favourable  and  the  young  apparently  healthy.  A 
good  many  animals  eat  the  after-birth,  which  is  said  to  contain  a 
substance  that  excites  the  secretion  of  milk,  and  the  eating  of  the 
young  may  be  suggested  by  the  habit. 

Lemurs  often  breed  in  captivity  and  are  extremely  good  mothers. 
As  in  man  and  true  monkeys,  there  is  usually  only  one  at  a  birth. 
It  clings  firmly  to  the  mother,  lying  horizontally  across  the  lower 
part  of  her  abdomen,  holding  on  by  its  hands  and  feet  and  with  its 
long  tail  twisted  round  the  back  of  the  mother.  The  mother, 
however,  helps  to  support  the  baby  by  her  own  tail,  which  she 
usually  curls  up  between  her  legs  over  the  body  of  the  infant  and 
then  twists  round  her  own  body.  Later  on,  when  the  young  is  more 
active,  it  is  often  carried  on  the  back  of  the  mother.  For  the  first 
day  or  two  the  mother  sits  upright  with  the  baby  lying  across  her 
abdomen,  and  bends  over  it  from  time  to  time  with  a  low  crooning 
noise.  Male  lemurs  take  no  interest  in  their  young  and  have  no 
share  in  protecting  them.  The  plate  (X)  shows  a  black-headed 
lemur  with  its  baby,  born  in  the  London  Zoological  Gardens, 
drawn  a  few  days  after  birth.  The  text-figure  (Fig.  30)  shows  the 
young  of  another  lemur,  when  much  older,  being  carried  on  the 
mother's  back. 

In  all  the  carnivores  the  young  are  born  in  a  helpless  con- 
dition, usually  blind,  although  new-born  lions  can  see,  and  remain 
with  the  mother,  sometimes  with  both  parents,  for  a  period  ranging 
from  a  few  weeks  in  some  of  the  smaller  creatures  to  even  more 
than  a  year.  The  large  predaceous  creatures  cover  great  distances  in 


PLATE  X 

FEMALE  BLACK-HEADED  LEMUR 
AND  YOUNG 

The  plate  shows  the  mother  with  her  baby  in  two  positions 

a  few  days  after  the  young  one  was  born  in  the  London 

Zoological  Gardens. 


166  CHILDH' 

\ved  in  exactly  the  igur  and  her  baby,  and 

ook  a  liveh  his  child,  but  did  :  e  in 

prot  it  in  any  r  on,  when  the  young  ape  began  to 

tak.  d  not  scramble  with  it  ties, 

in  the  usual  fasl;  ;eys  living  together,  but  they  showed  no 

is  of  shar  breed  quite  often  in  captivity, 

birth  usuaJJ  .:  place  in  the   sleeping-box.     They    often 

a    pa  tinct    which    is    not    infrequent    amongst 

mammals,  1:  rare  in  the  case  of  monkeys.     In  the  first  day 

or  two  i  v  kill  and  eat  her  young.     In  the  carni- 

vores this  perhaps  is  not  so  surprising.     When  the  cubs  are  feeble, 
or  d  i  ^uses,  i  t  would  not  be  unnatural  for  a  carnivorous 

mot]  often  with  young  and 

AJ^T  But  it  also  occurs 

con  v  ^TX^T/VT  rrv         •— AW^R      thy.     A 

T-^-U/  CI^A  ontaina 

enoitieoq  ov/t  ni  vdr>d  lorf  *&&  ^SB$k*1%wLtb§+g&tWR  of  the 


nobaoJ  zdl  ni  jiipy  ffiFlwDifeni/OY  9rfl  istU  evsb  ws^  -£ 


tremely  good  mothers. 
As  i?  monkeys,  there  is  usually  only  one  at  a  birth. 

It  ci  iying  horizontally  across  the  lower 

part  ,  holding  on  by  its  hands  and  feet  and  with  its 

long  -und  the  back  of  the   mother.    The  mother, 

•jpport  the  baby  by  her  own  tail,  which  she 
her  legs  over  the  body  of  the  infant  and 
n  body.     Later  on,  when  the  young  is  more 
<!  on  the  back  of  the  mother.     For  the  first 
upright  with  the  baby  lying  across  her 
from  time  to  time  with  a  low  crooning 
-•>  interest  in  their  young  and  have  no 
The   plate  (X)  shows  a  black-he: 
rn   in   the   London  Zoological  Gard 
The  text-figure 
much  older,  bt 

•  are  born  in   a   helpless    con- 
born  lions  can  see,  and  rer 
Barents,  for  a  period  ranging 
ler  creatures  to  even  i 
than  a  year.    The  large  \  ures  cover  great  distances  ir* 


BROOD-CARE  AMONG  MAMMALS 


167 


pursuit   of  their  prey,  but  usually  have  permanent  headquarters 

which  they  use  by  day  if  they  are  nocturnal,  or  at  night  if  they 

hunt  by  day.     The  lair  is  in  a  well-concealed  place,  capable  of 

defence,  in  the  middle  of  a  thick  forest-brake,  or 

in  dense  reeds,  or  in  a  rocky  recess  in  the  side  of 

a  hill,  or  in  a  hole,  burrow  or  hollow  tree.     In 

captivity,    the    mothers    always  retreat  to  the 

darkest  corner  of  their  enclosure  to  bring  forth 

their  young,  and  one  of  the  necessities  for 

successful    breeding   is  to    provide  a 

suitable    shelter   for  this  purpose. 

It  is  often  useful  to  provide  two, 

for  the  mother,  even  if  she  be 

not    disturbed,    is    restless 

after  the  cubs  are  born, 

and      frequently     will 

carry  them  from  one 

place  to   another 


until  she  finds 

a  nook  to  her 

liking.   It 

is     in 

the 

first 

few  days 

that    the 

young  run 

the     greatest 

risk  of  being 

eaten  by  the 

mother.       A 

bed   of  soft 

dry  earth, 

of  leaves 

or  litter, 

is    f r e -      Jv 

quently  scraped   up   beforehand.     When   pumas    live  in  a  place 

where  there  are   not  natural  caves  or  rocky  recesses  they  make 

a  lair  of  twigs  and  moss  in  some  dense  thicket,  with  an  overarching 

roof   of   evergreen   canes.     The  early  days  of  all   carnivores  are 

spent  in  a  nursery  of  this  kind,  and  the  mother  takes  scrupulous 


30.     Ring-tailed  Lemur  carrying 
its  young.     (After  POCOCK.) 


168  CHILDHOOD  OF  ANIMALS 

care  to  keep  it  sweet  and  clean,  whilst  she  licks  the  cubs  with  her 
rough  tongue  until  they  are  able  to  look  after  their  own  toilet 
or  to  lick  and  clean  each  other. 

The  duties  of  parental  care  among  carnivores  fall  chiefly  on  the 
mothers,  and  although  lions  and  tigers  and  not  a  few  of  the  larger 
cats  remain  in  pairs,  the  father  takes  little  interest  in  the  cubs.  For 
the  first  few  days  the  mother  does  not  leave  her  family  even  to  feed, 
but  afterwards  she  has  to  leave  them  from  time  to  time  to  go  out 
hunting  on  her  own  account.  Almost  the  first  sign  of  independent 
life  in  young  carnivores  is  their  power  of  wailing  and  screaming  ; 
they  are  very  noisy  babies,  and  in  captivity,  when  cubs  are  expected 
and  the  mother  has  retired  to  her  sleeping-den,  her  guardians  know 
when  the  happy  event  has  taken  place  by  hearing  the  squealing 
of  the  cubs.  Polar  bear  cubs  have  loud,  shrill  voices  and  seem  to 
cry  almost  continuously  from  the  moment  they  are  born.  Lion  and 
tiger  cubs,  leopard  and  jaguar  cubs,  have  thinner  and  smaller  voices 
at  first,  but  in  a  few  weeks  wail  like  cats.  The  voice  of  a  caracal 
cub,  when  it  is  so  young  that  it  cannot  yet  stand  upright,  can  be 
heard  all  over  a  house  if  the  little  creature  has  been  shut  up  alone. 
Hunger  is  certainly  not  the  chief  reason  why  they  cry  out,  for  they 
are  as  vehement  after  a  good  meal  as  before  it.  Cold  is  sometimes 
the  cause  of  the  complaint,  because  all  young  carnivores  like  to  be 
kept  very  warm,  and  will  bask  with  comfort  in  front  of  a  fire  until 
their  fur  feels  hot  to  the  touch.  What  they  want  is  companionship, 
and  their  loud  shrieks  when  they  are  left  alone  guide  the  mother 
to  them,  and  she  in  return  calls  to  them  with  a  special  note  unlike 
her  usual  purr  or  roar.  Many  carnivores,  as,  for  instance,  pumas  and 
caracals,  practically  never  use  their  voices  except  in  the  breeding 
season,  and  then  chiefly  as  a  call  between  the  mother  and  the  young. 

The  carnivorous  mother  always  carries  her  young  about  in  her 
mouth,  picking  them  up  by  the  loose  skin  on  the  back  of  the  neck, 
and  so  carries  them  back  to  the  lair  if  they  have  wandered  from  it, 
or  transports  them  to  new  quarters.  Although  the  cubs  or  kittens 
climb  over  the  mother  when  she  is  lying  down,  she  seldom  carries 
them  except  in  her  mouth.  A  polar  bear  in  the  London  Zoological 
Gardens,  however,  was  noticed  to  carry  her  cub,  not  in  her  mouth,  but 
tucked  under  her  arm.  It  is  generally  supposed  that  the  female  polar 
bear  makes  a  burrow  in  the  snow  in  late  autumn,  and  that  the 
one  or  two  cubs  are  born  inside  this  and  remain  there  throughout 
the  winter  while  the  mother  hibernates.  The  cubs  are  excessively 
small  compared  with  the  size  of  the  mother  and  grow  very  slowly 


BROOD-CARE  AMONG  MAMMALS  169 

for  the  first  few  months,  whilst  they  are  being  suckled.  But  Arctic 
explorers  are  frequently  visited  by  bears  during  winter,  and  polar  bears 
in  captivity  do  not  hibernate,  nor  show  the  slightest  signs  of  being 
less  active  and  less  ready  to  feed.  It  is  much  more  probable  that 
these  bears,  in  their  native  haunts,  hunt  seals  along  the  edge  of  the 
ice  even  in  winter,  and  make  only  temporary  burrows  in  the  snow, 
so  that  it  may  be  their  habit  to  transport  their  young  from  place  to 
place.  Raccoons  carry  their  young  on  their  backs,  and  it  is  probable 
that  some  of  other  carnivores  that  live  in  trees  have  similar  habits. 

Before  they  are  weaned,  young  carnivores  begin  to  scrape  off 
fragments  of  flesh  from  the  prey  that  the  mother  has  brought  home 
and  so  gradually  acquire  a  taste  for  their  future  food.  Before  they 
leave  the  lair  they  are  taught  the  elements  of  stalking  by  the  mother, 
who  lets  them  play  with  her  tail,  flicking  about  its  tip,  and  training 
them  to  seize  hold  of  it  and  worry  it.  As  soon  as  they  are  strong 
enough  they  are  taken  out  by  the  mother,  sometimes  by  both  parents, 
on  foraging  expeditions.  Family  parties  of  lions  have  often  been 
seen  by  African  hunters.  It  seems  that  it  takes  nearly  a  year  and  a 
half  for  young  lions  to  learn  the  business  of  stalking.  At  first 
they  go  out  with  the  parents  on  short  excursions  and  wait  behind 
until  the  kill  has  been  made,  when  they  rush  in  and  follow  the 
example  of  the  parents  in  tearing  the  prey  to  pieces.  During 
this  time  lions  frequently  prefer  an  easy  prey,  attacking  flocks  of 
sheep  or  goats  and  killing  more  than  they  require  for  food.  After 
the  first  year,  when  the  canine  teeth  are  powerful,  the  young  lions 
are  allowed  to  stalk  and  kill  their  own  prey,  but  the  parents  watch 
close  at  hand,  to  be  ready  with  assistance  if  necessary.  The  young 
animals  at  first  do  their  work  in  a  blundering  fashion,  and  their  kill 
can  be  recognised  by  the  clumsy  way  in  which  it  is  mauled.  Pumas 
go  out  hunting  with  the  mother  when  they  are  only  a  few  weeks  old. 
Polar  bears  teach  their  cubs  to  fish  and  to  swim.  The  smaller 
carnivores  all  have  the  same  kind  of  early  training.  Young  badgers 
can  often  be  seen  playing  with  their  mother  at  the  edge  of  their 
"  earth  "  when  they  are  only  three  weeks  old.  Later  on  they  go  out 
with  her,  trotting  along  in  single  file  behind  her  in  the  hedgerows 
and  learning  where  to  find  what  is  good  to  eat  and  how  to  catch  it. 
Polecats,  ferrets  and  weasels  bring  back  small  creatures  such  as  mice 
for  their  young  to  worry  and  eat,  and  later  on  take  them  out  hunting. 

Many  of  the  animals  which  belong  to  the  group  of  carnivores  are 
not  really  carnivorous,  but  live  on  fruits,  shoots,  seeds  and  other 
vegetable  matter,  and  they  also  learn  from  their  mothers  how  to 


I7o  CHILDHOOD  OF  ANIMALS 

obtain  food.  That,  however,  is  a  less  difficult  business,  and  it  is 
the  true  hunters  of  living  things  that  have  most  to  learn.  No 
animal  likes  being  caught  and  eaten,  and  the  natural  victims  of  the 
carnivores  have  learnt  intense  wariness.  They  have  acute  senses 
of  smell  and  of  hearing,  and  meet  the  cunning  and  strength  of 
their  enemies  with  swiftness  and  prudence.  The  young  carnivores 
have  to  learn  to  stalk  them  against  the  wind,  to  lie  in  wait  for  them 
at  their  drinking-places,  to  make  the  right  springs  at  the  right  time, 
and  to  strike  the  right  blow  with  claws  or  teeth.  And  whilst  they 
are  learning  these  things  from  their  parents,  and  coming  to  a  know- 
ledge of  their  own  weapons,  they  have  also  to  learn  to  distinguish 
between  friend  and  prey,  to  use  their  teeth  and  claws,  roughly 
no  doubt  but  only  playfully,  with  their  brothers  and  sisters  and 
parents,  and  to  reserve  the  full  strength  of  these  for  creatures  they 
wish  to  kill.  It  would  be  a  shorter  and  simpler  business  if  they  had 
to  develop  only  their  instincts  of  ferocity,  to  learn  to  use  their 
natural  powers  only  for  deadly  purposes.  But  they  have  the  double 
lesson  to  learn  and  they  do  learn  it.  Certainly,  carnivorous  animals 
will  engage  in  fierce  contests,  especially  from  motives  of  rivalry  or 
jealousy,  but  in  this  they  do  not  differ  from  other  animals  which 
are  not  naturally  predatory.  As  a  group  they  are  not  the  most 
olifficult  to  put  together  or  to  keep  together,  and,  except  for  an  occa- 
sional quarrel  over  food  or  over  a  mate,  even  the  fiercest  carnivores 
associate  in  peace,  and  are  naturally  friendly  rather  than  quarrelsome 
both  with  one  another  and  with  human  beings,  or  even  allied  species. 
The  early  life  of  ruminants  is  extremely  different  from  that  of 
young  carnivores.  In  the  first  place  they  are  wanderers.  They 
have  to  travel  long  distances  in  search  of  water  ;  they  must  migrate 
from  place  to  place  to  find  the  great  bulk  of  vegetation,  of  young 
foliage  or  herbage  that  they  require  as  food.  Even  the  large  and 
swift  giraffe  whose  size  protects  it  from  all  but  the  most  powerful 
of  the  carnivores,  the  strong  and  savage  buffaloes  which  not  infre- 
quently repulse  tigers  successfully,  the  agile  goats  and  mountain 
antelopes  which  seek  safety  on  the  high  pinnacles  of  rocks,  and  still 
more  the  small  and  defenceless  gazelles  and  brockets,  keep  alive  only 
by  incessant  watchfulness  and  by  swift  flight  from  their  enemies. 
They  have  no  permanent  home,  but  from  day  to  day,  from  hour 
to  hour,  almost  from  minute  to  minute  they  must  be  ready  to  rush 
off.  Their  habit  of  rumination  is  itself  an  adaptation  to  this 
shifting  life.  They  do  not  chew  their  food  as  they  crop  it,  but  as 
quickly  as  may  be  fill  their  huge  paunches  with  a  great 


BROOD-CARE  AMONG  MAMMALS  171 

load  of  green  vegetation,  and  then  fly  to  a  more  sheltered  place 
to  lie  down  and  chew  the  cud.  The  mothers  make  no  preparation 
beforehand  for  their  young,  but  retire  for  a  few  minutes  to  a  thicket 
and  then  drop  the  calves  or  lambs.  One  is  the  most  usual  number 
at  a  birth,  and  twins  or  triplets  are  almost  as  rare  as  amongst  human 
beings.  The  young  are  born  clothed  with  hair,  with  their  eyes  open 
and  their  senses  alert,  and  in  a  very  short  time,  almost  as  soon  as 
the  mother  has  licked  them,  are  able  to  follow  her.  She  then  rejoins 
the  herd  if  the  animals  are  gregarious.  The  mothers,  however,  are 
very  devoted  to  their  young,  and  if  there  is  a  herd  the  bulls  will 
combine  in  defence  of  the  cows  with  their  calves,  whilst  in  other 
cases  there  is  usually  a  family  party  consisting  of  the  bull,  one  or 
two  cows  and  their  calves. 

A  new-born  giraffe  is  able  to  stand  up  in  about  twenty  minutes, 
and  to  run  freely  in  a  day  or  two  ;  in  three  weeks  it  begins  to  nibble 
herbage  and  in  four  months  to  chew  the  cud.  So  also  all  young 
ruminants  begin  to  chew  the  cud  only  some  weeks  after  birth,  and 
the  young,  during  the  earlier  part  of  their  life,  resemble  their  non- 
ruminating  ancestors.  Deer  are  rather  feebler  than  most  of  the 
ruminants  at  birth.  Very  often  they  have  to  be  helped  up  by  the 
mother,  and  usually  lie  for  two  or  three  days  in  a  thicket  before  they 
are  able  to  follow  the  parent.  Wild  cattle,  sheep  and  goats  are 
able  to  move  actively  in  a  good  deal  less  time  than  deer,  and  chamois 
and  antelopes  are  extremely  active  almost  at  once,  beginning  to 
play  and  being  able  to  follow  the  mother  when  they  are  a  few 
hours  old.  The  young  Springbuck  represented  on  Plate  XII 
(p.  250)  was  drawn  from  a  kid  a  few  hours  after  its  birth  in  the 
London  Zoological  Gardens.  Young  camels  are  active  and  playful 
and  can  move  about  almost  at  once.  They  begin  to  eat  in  a  few 
weeks,  but  suckle  for  nearly  a  year. 

The  Even-toed  Ungulates  that  do  not  ruminate,  the  pigs,  peccaries 
and  hippopotami,  differ  a  good  deal  in  their  habits  from  the 
ruminants.  They  are  less  disposed  to  seek  safety  in  flight,  the  swine 
and  peccaries  being  well  capable  of  defending  themselves  against 
most  enemies,  and  the  hippopotami  having  few  enemies  to  fear  in  the 
rivers  they  inhabit.  Wild  swine  and  peccaries  usually  produce  their 
young  in  a  dark  and  secret  den,  in  the  recesses  of  a  cave,  in  deep  brush- 
wood, or  even  in  the  hollow  of  a  huge  tree  trunk.  The  families  are 
rather  large,  a  litter  usually  containing  from  four  to  a  dozen,  but 
the  smaller  numbers  are  more  frequent  in  wild  animals  than  in  the 
domesticated  races.  The  little  pigs  are  feeble  at  birth  and  are 


172  CHILDHOOD  OF  ANIMALS 

sedulously  guarded  by  the  mother  in  her  lair  for  about  a  fortnight; 
after  which  they  follow  her  abroad  on  her  foraging  expeditions,  but 
are  carefully  watched  by  her  for  many  months.  The  hippopotamus 
brings  forth  her  young  in  a  reedy  thicket,  generally  on  an  island. 
One  is  the  usual  number,  and  the  baby  is  active  from  the  first  and  is 
able  to  swim  before  it  can  walk.  In  captivity  a  hippopotamus  has 
been  born  actually  in  the  water  on  more  than  one  occasion,  and 
the  mother  has  usually  shown  herself  rather  indifferent,  whilst  the 
father  takes  no  notice  at  all  of  the  young  one.  In  the  wild  state, 
however,  the  young  one  stays  with  the  mother  for  a  long  time, 
probably  for  several  years,  and  is  carried  on  her  back  in  the  water. 


FIG.  31.     Hippopotamus  carrying  its  young. 

African  travellers  have  described  the  sudden  apparition  of  a  small 
hippopotamus  above  the  water,  rising  up  until  it  appeared  to  be 
standing  on  the  surface,  but  really  being  carried  on  the  mother's 
back  (Fig.  31).  When  the  female  reaches  the  bank,  the  little  one 
slips  off  and  follows  her  on  foot. 

The  Odd-toed  Ungulates — the  horses,  asses  and  zebras,  and  the 
tapirs  and  rhinoceroses — give  birth  almost  invariably  to  a  single 
young  one  without  having  made  any  preparation  beforehand.  Foals 
can  see  and  stand  in  a  few  minutes  after  their  birth,  and,  although 
they  are  feeble  on  their  legs,  can  very  soon  follow  the  mother.  In 
the  wild  condition  these  animals  live  in  herds,  and  the  stallions 
combine  to  protect  the  mares  and  foals  when  they  are  attacked 
by  lions  or  wolves,  but  as  they  prefer  to  seek  safety  in  flight,  and  as 
the  herd  has  to  move  about  in  search  of  food,  the  foals  must  be 
active  very  soon.  Tapirs  are  often  born  in  captivity,  and,  like 
horses,  are  active  in  a  few  minutes.  Extremely  little  is  known  about 
the  breeding  habits  of  rhinoceroses,  but  the  young  are  plump, 


BROOD-CARE  AMONG  MAMMALS  173 

strong  and  active  and  follow  the  mother  for  a  very  long  time, 
for  individuals  nearly  full  grown  and  certainly  six  or  seven  years  old 
have  been  found  running  with  the  mother  and  still  suckling.  A 
young  African  rhinoceros  came  to  the  London  Zoological  Gardens 
in  charge  of  a  black  boy,  for  whom  it  showed  great  affection, 
screaming  loudly  when  the  boy  went  off,  and  giving  a  low  "  whinny  " 
of  pleasure  when  he  returned.  It  was  a  considerable  time  before 
the  young  animal  would  take  either  milk  or  sugar-cane,  the  two 
chief  parts  of  its  food,  from  any  one  except  its  special  guardian. 

Elephants  are  much  more  active  creatures  than  is  easy  to  suppose 
from  watching  their  sedate  and  leisurely  gait  in  captivity.  They 
travel  enormous  distances,  moving  very  quickly  and  climbing  almost 
precipitous  mountain  slopes  with  skill,  lightness  and  agility.  A 
single  calf  is  produced  at  a  birth  and  is  able  to  move  and  follow 
the  mother  almost  at  once.  The  mother  is  devoted,  incessantly 
stroking  the  young  with  her  trunk,  and  defending  it  rather 
savagely  from  any  rash  intruder.  The  baby  suckles  with  its 
mouth  in  the  ordinary  fashion  of  a  young  mammal,  and  does 
not  use  its  trunk  for  drinking  or  even  for  picking  up  food  for 
some  weeks.  The  calf  remains  with  the  mother  for  several  years 
until  it  is  very  well  grown. 

The  dassies,  rock-rabbits  or  hyraxes,  although  they  differ  ex- 
tremely in  size  from  elephants,  are  probably  as  nearly  related  to 
them  as  to  any  other  living  mammals.  They  live  in  rocks  or  in 
tall  forest  trees  and  the  mothers  usually  have  a  family  of  three. 
The  young  hyraxes  are  about  as  big  as  rats  and  are  thickly 
covered  with  very  dark  hair.  They  are  active  from  the  first  and 
are  carried  by  the  mother  on  her  back  (Fig.  32).  Although  they  are 
often  compared  with  rabbits,  they  are  quite  different  in  habit  and 
disposition,  being  extremely  intelligent  and  affectionate  and  most 
plucky  and  well  capable  of  defending  themselves.  My  young 
tree-hyrax  was  once  introduced  by  accident  to  a  palm-civet,  which, 
although  tame,  was  accustomed  to  try  its  teeth  on  everything  and 
was  a  good  many  times  the  size  and  weight  of  my  little  animal.  The 
hyrax,  however,  at  once  raised  its  hair  almost  like  the  spines  on  a 
porcupine,  opened  its  white  dorsal  patch  and  rushed  in  at  the  civet 
with  a  loud  shriek  of  challenge,  gave  it  a  sharp  bite,  and  then 
quickly  sprang  back  a  foot  or  two,  and  stood  bristling  and  alert 
ready  for  a  second  charge.  This  was  unnecessary,  as  the  civet  was 
routed  and  fled  shrieking  to  its  owner. 

The  flesh-eating  carnivores  and  the  herbivorous  ungulates  form 


174 


CHILDHOOD  OF  ANIMALS 


two  of  the  most  important  and  strongly  contrasted  groups  of 
mammals.  The  contrast  is  specially  evident  in  the  case  of  the 
young.  The  baby  carnivores  are  helpless  at  first  and  are  produced 


FIG.  32.     Tree-hyrax  carrying  its  young. 

in  well-hidden  lairs.  For  some  time  they  depend  entirely  on  the 
devotion  of  their  parents  and  are  fed,  protected  and  trained  by  them. 
When  they  are  quite  small  they  are  often  carried  about  by  the 
mothers,  usually  in  her  mouth,  but  in  a  few  rare  cases  in  another 
fashion,  by  polar  bears  under  the  arm,  by  raccoons  on  the  back. 
In  their  young  days,  when  the  mother  goes  hunting,  she  has  to  leave 
the  cubs  behind,  and  if  they  wander,  discovers  them  chiefly  by  the 
voice.  It  is  only  when  they  are  weeks  or  months  old  that  they  begin 


BROOD-CARE  AMONG  MAMMALS  175 

to  follow  her.  Young  ungulates  have  to  follow  the  mothers  almost 
from  the  first ;  it  is  only  in  a  few  rare  cases,  such  as  the  pigs,  that  they 
are  kept  for  any  time  in  a  lair.  It  is  still  rarer  for  them  to  be  carried 
by  the  mother  ;  the  hippopotamus  and  the  hyrax  are  very  unusual 
in  this  respect,  and  the  former  has  habits  different  from  those  of 
all  other  ungulates,  whilst  the  latter  belongs  to  a  peculiar  and  isolated 
group.  Young  ungulates,  like  all  mammals,  are  suckled  by  the 
mothers,  but  are  not  fed  by  her  in  any  other  way.  Certainly  parental 
affection  is  strong,  but  it  is  the  business  of  the  young  one  to  find,  follow 
and  stick  to  the  mother  rather  than  for  the  mother,  as  amongst  car- 
nivores, to  take  the  initiative.  And  the  most  important  difference  of 
all  is  that  whilst  no  doubt  the  young  find  the  feeding-grounds  by 
following  the  mother,  there  is  practically  no  real  training  of  the 
young  by  their  parents. 

The  Insectivora  are  the  living  survivors  of  a  very  ancient  type  of 
mammal,  certainly  older  than  the  carnivores,  and  perhaps  repre- 
senting their  ancestors.  Most  of  them  are  small  and  shy  creatures, 
lurking  by  day  in  holes  or  burrows  and  coming  out  at  night  in 
search  of  worms  and  beetles.  The  family  is  generally  small,  four 
or  five  at  most,  and  is  born  in  a  helpless  condition,  frequently  blind 
and  nearly  naked.  The  female  hedgehog  prepares  a  nest  of 
moss  and  leaves,  placed  so  that  it  is  sheltered  from  the  rain,  and 
the  naked  young  are  too  helpless  even  to  roll  themselves  up  at 
first.  In  a  week  or  two  they  begin  to  play,  the  spines  harden,  and 
the  mother  teaches  them  their  future  diet  by  bringing  worms  and 
beetles  to  them.  The  female  shrew  constructs  a  globular  nest  at  the 
end  of  a  blind  burrow  and  lines  it  with  soft  hair  and  leaves.  So  also 
the  mole  selects  a  spot  where  two  of  its  burrows  meet,  and  constructs 
a  globular  chamber,  very  different  from  the  elaborate  fortress 
which  is  its  usual  home,  to  serve  as  a  nursery  for  the  helpless  young. 

The  members  of  the  huge  group  of  rodents  vary  in  size  from  the 
South  American  capybara,  which  may  reach  four  feet  in  length,  to 
the  pigmy  fieldmouse,  the  smallest  of  living  mammals,  and  although 
they  are  all  gnawing,  chiefly  vegetarian  creatures,  differ  much  in 
habits.  Amongst  them  are  the  most  prolific  of  mammals,  but  the 
rapid  rate  of  multiplication  is  achieved  by  the  shortening  of  the 
period  of  youth,  and  by  the  early  age  at  which  individuals  begin  to 
breed,  rather  than  by  the  size  of  the  broods.  In  many  cases  there 
are  only  two,  three,  or  four  born  at  a  time,  although  there  are  some 
cases  where  the  number  may  reach  ten  or  a  dozen.  In  most  rodents 
the  young  are  born  naked,  blind  and  helpless,  and  the  young  depend 


176  CHILDHOOD  OF  ANIMALS 

on  the  mother  until  they  are  nearly  full  grown.  I  do  not  know  of 
any  instances  in  which  the  males  take  care  of  the  young  ;  generally 
they  either  neglect  them  altogether  or  attack  them  and  persecute 
them.  In  a  few  cases  the  young  are  born  in  a  high  state  of  develop- 
ment, recalling  that  of  the  ruminants.  Young  hares  are  able  to  see 
and  to  follow  the  mother  in  a  few  hours  after  they  are  born.  Young 
guinea-pigs  are  furred,  have  their  eyes  open  and  are  active  almost  at 
once,  and  in  a  few  days  begin  to  nibble.  Agoutis  differ  from  their 
parents  only  in  size  at  birth,  and  almost  at  once  begin  to  run  about 
actively.  Porcupines  also  have  their  eyes  open  when  they  are  born  ; 
their  spines  are  present,  but  are  white  and  soft,  and  it  is  only  in  a  few 
days  that  they  become  hard  and  serve  as  a  protection.  In  these 
cases,  however,  the  animals  live  more  in  the  open  without  a  per- 
manent abiding-place  and,  like  ruminants,  have  to  escape  from  their 
enemies  by  swiftness. 

^  In  most  rodents  brood-care  begins  before  the  young  are  born,  and 
the  mother  selects  and  prepares  a  nursery  for  her  family.  Rabbits 
live  in  communities,  and  the  burrows  of  a  warren  form  a  complicated 
set  of  underground  passages  which  lead  into  each  other  and  are  used 
in  common.  The  females,  however,  dig  out  circular  chambers 
opening  off  the  main  burrows,  generally  with  two  or  three  exits. 
These  they  line  with  leaves,  soft  grass,  and  masses  of  fur  plucked 
from  their  own  breasts,  and  the  blind  and  naked  young  are  guarded 
for  some  weeks  in  these  warm  recesses.  Squirrels  construct  winter 
nests  in  the  forks  of  branches  and  store  provisions  against  hard 
times.  In  early  summer  they  build  more  open  nests  far  out 
on  slender  branches  and  there  the  blind  and  naked  young  are 
cherished  and  protected  for  many  months.  Hamsters  construct 
most  elaborate  dwellings  underground,  and  store  up  in  them  a  great 
provision  'of  food  for  the  winter,  but  in  the  breeding-season  the 
females  hollow  out  larger  and  much  less  elaborate  dwellings, 
just  under  the  surface  of  the  ground,  in  which  the  naked  young  are 
reared.  All  the  rats  and  mice  make  most  comfortable  nurseries  for 
the  young,  collecting  quantities  of  soft  materials,  such  as  wool,  rags, 
moss,  paper,  hair  or  feathers,  and  arranging  them  in  a  burrow  or 
hole.  The  harvest-mouse  weaves  a  nest  which  can  be  compared 
only  with  some  of  the  most  elaborate  habitations  constructed  by 
birds.  It  is  made  of  narrow  grasses,  woven  carefully  into  a  globe  about 
the  size  of  a  cricket  ball,  and  is  suspended  to  stout  herbs  or  blades 
of  corn.  The  walls  are  very  thin,  and  there  is  no  special  opening, 
the  mother  squeezing  out  or  in  through  the  meshes.  The  family 


BROOD-CARE  AMONG  MAMMALS  177 

is  rather  large,  seven  or  eight  being  the  usual  number,  and  these  lie 
tightly  packed  inside  the  meshes  of  the  nest.  Dormice  make  a 
nest  of  the  same  kind,  but  generally  oval  rather  than  globular,  and 
suspended  high  up  in  a  thick  hedge. 

The  elaborate  dams  which  beavers  make  by  cutting  down  trees, 
collecting  twigs  and  plastering  over  the  tangled  mass  with  mud,  keep 
the  water  at  a  constant  level,  and  in  the  pools  thus  formed  the 
carefully  built  lodges  are  constructed.  These  always  have  an 
entrance  under  the  water  and  at  least  one  on  land.  Small 
branches  are  fastened  to  the  dam  and  stored  in  the  lodge,  and  in 
winter  when  food  is  scarce  the  beavers  take  these  above  water  and 
strip  off  the  bark  and  eat  it.  The  special  chambers  in  which  the 
young  are  born  are  lined  with  chips  of  wood  quite  differently 
arranged  from  the  stores  of  edible  twigs.  The  young  are 
born  naked  and  blind ;  the  mother  suckles  them  and  keeps 
them  warm  for  a  month  and  then  brings  them  twigs,  the  bark 
of  which  they  begin  to  eat.  In  six  weeks  they  follow  her  out  to 
her  usual  haunts,  but  remain  under  her  superintendence  for  two 
years,  after  which  they  pair  and  set  up  in  life  for  themselves.  The 
intelligence  of  beavers  is  much  higher  than  that  of  other  rodents,  and 
the  long  period  of  youth,  under  the  tutelage  of  the  mother,  is 
occupied  in  learning  not  only  what  is  necessary  to  the  individual, 
but  the  art  of  living  with  other  beavers  in  a  well-disciplined  com- 
munity, doing  work  for  the  common  good. 

The  beaver  towns  are  only  an  extreme  result  of  the  gregarious 
habits  found  in  most  members  of  the  group.  Even  when  the  period 
of  youth  is  very  short,  and  the  mother  is  soon  occupied  with  the 
cares  of  a  new  family,  the  deserted  young  remain  together  for  a 
time.  Young  hares,  when  the  mother  has  left  them,  haunt  the 
form  in  which  they  were  born,  and  play  together  for  a  good  many 
months  until  they  are  nearly  full  grown,  when  they  have  to  scatter 
because  of  the  special  risks  of  their  mode  of  life  in  the  open  fields 
and  woods.  More  often  rodents  live  together  in  some  kind  of 
community,  and  it  is  very  rare  to  find  only  a  single  pair  in  any  suitable 
place.  Sometimes  they  burrow  close  together,  forming  assemblages 
like  the  warrens  of  rabbits,  or  the  villages  of  prairie-dogs  or  marmots. 
Sometimes  it  is  merely  that  they  occupy  the  same  corner  of  a  wood 
or  field,  the  same  group  of  trees  or  heap  of  rocks.  They  retain  a 
kind  of  communal  instinct.  Squirrels  will  desert  a  wood  in  a  body, 
and  in  the  north  great  armies  of  them,  simultaneously,  for  no  apparent 
reason,  but  especially  in  severe  winters,  move  in  a  direct  line  over 

C.A.  M 


i;8  CHILDHOOD  OF  ANIMALS 

immense  distances.  The  similar  migrations  of  hares,  Norway  rats 
and  lemmings  are  still  better  known.  The  animals  keep  together  by 
an  instinct  of  gregariousness,  and  will  perish  in  great  numbers  if  an 
impassable  river  or  branch  of  the  sea  lie  across  their  chosen  route. 
Simultaneous  migrations  on  a  smaller  scale  frequently  happen. 
There  is  a  fine  colony  of  prairie-dogs  living  on  a  private  estate  in 
Sussex.  Recently  a  number  of  them,  for  no  obvious  reason,  as 
there  was  plenty  of  room  and  plenty  of  food,  moved  off  more  than  a 
mile,  crossing  very  irregular  ground,  and  settled  down  in  another 
field.  Rats  or  mice  will  leave  a  particular  house  or  ship  almost 
in  a  body,  and  this  habit  is  useful  when  it  is  necessary  to  get 
rid  of  these  pests.  If  for  some  weeks  a  few  are  trapped  or  poisoned 
every  day,  the  whole  body  will  desert  the  dangerous  place,  and  even 
newcomers,  in  search  of  convenient  quarters,  will  refuse  to  settle 
down  for  weeks  or  months. 

Rodents  usually  follow  the  mother,  and  afterwards  each  other,  in 
single  file,  running  along  in  well-marked  tracks  leading  from  their 
bolt-holes  to  the  feeding-grounds.  The  South  American  coypu, 
a  large  aquatic  rodent,  makes  a  burrow  in  the  bank  of  a  lake  or 
stream  with  the  aperture  under  the  water-level,  or,  if  there  is  not 
a  suitable  position  for  this  kind  of  nursery,  constructs  a  platform- 
nest  in  the  thick  reeds  alongside  a  stream.  Six  to  nine  young  are 
produced  at  a  time,  active  and  furry,  and  are  very  soon  able  to  follow 
the  mother  to  the  water.  There  some  of  them  climb  on  her  back  and 
are  carried  about  as  she  swims,  whilst  the  others  swim  alongside. 
The  nipples  of  the  milk  glands,  instead  of  being  placed  in  the  usual 
fashion  on  the  under  surface  of  the  mother,  are  arranged  in  a  row  at 
each  side,  very  high  up  and  nearer  the  middle  line  of  the  back,  so  that 
the  young  are  able  to  suckle  either  as  they  swim  alongside  or  as 
they  crouch  on  the  back. 

Very  little  is  known  as  to  the  breeding  habits  of  sloths,  armadillos 
and  anteaters.  Sloths  spend  their  whole  lives  in  trees,  sluggishly 
creeping  along  the  lower  sides  of  branches,  to  which  they  hang  by 
their  curved  claws.  The  young  are  born  fully  developed,  no  special 
nest  being  made,  and  are  carried  about  by  the  mother,  clinging  to 
her  hair  with  their  long  claws  and  clasping  her  firmly  round  the 
neck  with  their  arms.  Anteaters  use  their  powerful  claws,  not  for 
burrowing,  but  for  digging  out  the  ants  and  termites  on  which  they 
feed.  They  make  a  lair  in  thick  brushwood,  and  so  far  as  is  known 
produce  a  single  young  one  at  a  time.  This  is  fully  clothed,  and  is 
carried  about  by  the  mother  on  her  back  for  many  months.  The 


BROOD-CARE  AMONG  MAMMALS 


179 


armadillos  and  pangolins  all  burrow,  digging  out  very  large 
chambers  at  the  end  of  a  long  tunnel.  In  these  the  young  are  pro- 
duced, usually  three  or  four  at  a  litter.  The  scales  are  at  first  pale 
and  soft,  and  the  young  remain  in  concealment  for  a  considerable 
time. 

In  all  the  marsupials  the  young  are  born  in  a  very  imperfect 
condition  and  are  at  once  attached  to  the  teats  of  the  mother. 
These  are  placed  far  back  on  the  body  inside  the  marsupial  pouch 
when  that  is  present.  The  number 
of  young  at  a  birth  varies,  but 
it  is  never  very  large,  in  most 
cases  one  or  two.  The  little 
animals  are  blind  and  naked, 
and  even  unable  to  suck.  Each 
is  attached  to  a  nipple,  and  its 
mouth  grows  into  a  sort  of  tube, 
which  is  sometimes  so  firmly 
attached  to  the  mother  that  it 
cannot  be  torn  away  without 
bleeding. 

As  the  young  are  always  carried 
and  kept  warm  by  the  body  of 
the  mother,  it  is  seldom  that  any 
preparations  are  made  before 
birth.  The  little  brush-tailed 
wallaby,  however,  and  the  rabbit- 
eared  bandicoot  seek  out  hollows 
in  the  ground,  and  roof  them  over 
skilfully  with  grass  and  twigs, 
and  a  large  number  live  in  hollow 
trees  or  scrape  out  burrows  in  the 

soil.  Whilst  it  is  not  so  surprising  that  the  mothers  of  young 
born  with  fur  more  or  less  like  their  own,  or  of  squeaking,  soft  little 
creatures  which  snuggle  against  them  and  seek  the  nipple  of  their 
own  accord,  should  show  maternal  instinct,  it  is  extraordinary  that 
a  marsupial  mother  should  even  take  notice  of  the  naked,  almost 
inanimate  and  quite  helpless  offspring,  and  still  more  so  that  she 
should  take  it  up  with  her  tongue  and  convey  it  to  the  nipple. 

All  the  kangaroos,  wallabies  and  their  immediate  allies  have  a 
marsupial  pouch  in  the  female.  This  is  a  deep  pocket  in  the  furry 
coat,  with  the  mouth  opening  forwards  and  protected  by  a  circular 


FIG.  33.     Tree-kangaroo  with  young 
in  pouch. 


180  CHILDHOOD  OF  ANIMALS 

band  of  muscle  so  that  the  female  can  shut  it  up  to  an  extremely 
small  hole  or  open  it  out  widely.  For  a  period  lasting  from  a  week 
in  the  smaller  ones  to  several  weeks  in  the  larger  animals,  the 
infant  remains  motionless  inside  the  pouch  firmly  attached  to  the 
nipple.  It  is  not  even  able  to  suck,  but  has  to  have  the  milk 
squirted  into  its  mouth  by  the  mother.  It  then  acquires  a  hairy 
coat,  leaves  the  nipple,  and  begins  from  time  to  time  to  push  its  head 
out  of  the  opening  of  the  pouch  and  takes  its  first  view  of  the  world 
(Fig.  33).  Soon  after  its  first  appearance  it  begins  to  nibble,  and 
as  the  mother  stoops  down  to  crop  grass  or  hay,  the  head  of  the 
youngster  is  thrust  out  and  it  also  begins  to  pick  at  food.  Gradually 
it  learns  to  push  out  its  head  more  and  more,  and  even  its  fore-paws, 
but  as  soon  as  the  mother  is  startled  and  sits  up  to  look  towards 
the  source  of  danger,  the  young  one  retreats  into  the  pouch;  leaving 
only  its  head  with  bright  twinkling  eyes  visible.  Still  later  on  the 
young  one  occasionally  comes  out  of  the  pouch  altogether,  and 
feeds  on  its  own  account,  hopping  near  the  mother.  At  the  first 
sign  of  danger,  however,  the  mother  stoops  down,  opens  the  pouch 
widely,  and  the  young  one  bolts  into  it  head  first,  and  then  wriggles 
round  until  it  has  reached  its  favourite  position  with  only  the  head 
protruding.  Kangaroos  give  birth  only  once  a  year,  and  long  after 
the  young  one  is  much  too  big  to  enter  the  pouch  it  keeps  with  its 
mother,  and  tries  to  suckle  by  thrusting  its  head  into  its  former 
home.  In  some  of  the  omnivorous  and  carnivorous  marsupials,  as, 
for  instance,  the  thylacine,  the  pouch  opens  backwards,  and  these 
are  quadrupedal  in  gait,  not  hopping  on  their  hind-legs  and 
tail  like  the  kangaroos  ;  in  others  it  is  present  only  in  the  form  of 
temporary  folds  of  the  skin,  and  in  others  again  there  is  no  trace 
of  it. 

All  the  marsupials,  except  perhaps  the  fierce  thylacine  and  the 
Tasmanian  devil,  are  preyed  on  by  other  marsupials,  or  by  large 
eagles  and  other  birds-of-prey,  and  escape  by  flight.  If  the  young  are 
small  enough  they  are  carried  in  the  pouch  of  the  mother,  or  run  off 
at  her  heels.  In  a  few  cases,  however,  especially  in  arboreal  forms, 
the  young  are  carried  on  the  back  of  the  mother.  The  phalangers 
leap  rapidly  from  bough  to  bough,  or  run  up  almost  vertical  branches 
with  the  greatest  ease,  and  the  females  are  often  to  be  seen  with  one 
or  more  young  clinging  to  their  fur.  The  little  koala,  or  tree-bear 
(Fig.  34),  a  gentle,  inoffensive  creature,  carries  its  single  cub  on  its 
back.  The  American  woolly  opossums  have  long  tails,  the  lower  surface 
of  which  is  scaly  and  used  for  grasping  branches.  The  females  carry 


BROOD-CARE  AMONG  MAMMALS 


181 


FIG.  34.     Koala  carrying  its  young. 


FIG.  35.     Opossum  carrying  its  young. 


1 82  CHILDHOOD  OF  ANIMALS 

their  young  on  their  backs,  and  each  little  creature  supports  itself 
by  twisting  the  end  of  its  tail  round  the  tail  of  the  mother  (Fig.  35). 
Male  marsupials  appear  to  take  no  interest  in  their  families  and 
do  not  assist  in  any  way  in  the  work  of  protecting  them. 

Thus,  in  many  different  ways,  first  in  the  womb,  afterwards  at  the 
breast,  keeping  them  warm,  protecting  and  educating  them,  the 
mothers  of  mammals  are  in  very  close  relations  with  their  young, 
and  in  a  smaller  but  considerable  number  of  cases  the  fathers  take 
some  part  of  the  burden  of  bringing  up  the  family.  The  first  result  is 
an  economy  of  life,  for  a  much  larger  proportion  of  the  young  that  are 
born  have  a  chance  of  escaping  the  perils  of  youth  and  inexperience 
than  in  any  other  group  of  the  animal  kingdom.  Next,  this  intimate 
association  has  led  to  a  high  development  of  the  emotional  and 
intellectual  powers.  In  watching  the  relations  between  young 
mammals  and  their  mother,  we  cannot  avoid  using  the  words  and  the 
ideas  which  we  would  use  of  the  human  race,  and  cannot  doubt 
but  that  affection  and  tenderness,  devotion  and  anxiety  are 
experienced  in  the  same  way,  if  not  to  the  same  degree,  as  amongst 
human  beings,  and  our  kinship  with  animals  is  brought  home  to  us 
far  more  closely  than  by  the  best-reasoned  anatomical  arguments. 


CHAPTER  XII 
THE  FOOD  OF  YOUNG  ANIMALS 

WHATEVER  be  the  diet  of  fully  grown  animals,  the  young 
require  food  that  is  easy  to  digest  and  that  contains  much  nutriment 
in  proportion  to  its  bulk.  Fully  grown  animals  have  strong  diges- 
tions and  usually  powerful  jaws  or  teeth,  or  some  other  natural 
tools  with  which  they  tear  and  grind  and  pulp  great  masses  of 
tough  material  and  extract  from  it  whatever  nutritious  matter  it 
may  contain.  Young  animals  cannot  easily  deal  with  such  sub- 
stances ;  they  must  have  their  food  in  as  concentrated  a  form  as 
possible,  and  composed  of  materials  as  like  the  substance  of  their 
own  flesh  and  blood  as  possible.  It  is  curious  that  there  is  a  similar 
difference  between  the  diet  of  green  plants  and  that  of  their  seedlings. 
The  mature  plants  stretch  their  leaves  into  the  air,  extracting 
from  the  thin  gases  of  the  atmosphere  the  necessary  chemical 
substances  to  build  up  starch  or  sugar,  whilst  their  rootlets,  twisting 
through  the  soil,  pour  out  a  corrosive  juice  which  dissolves  the 
hard  granules  of  mineral  matter,  and  so  enables  them  to  absorb 
other  necessary  materials.  The  young  seedlings  cannot  subsist 
on  such  a  meagre  fare  ;  they  live  on  the  highly  concentrated  food 
prepared  for  them  and  packed  round  them  within  the  seed-wall, 
and  digest  it  by  digestive  juices  not  very  different  from  those  of 
an  animal.  In  mammals  where  the  reduction  of  families  and 
parental  care  has  reached  its  highest  point,  the  first  food  and  the 
only  food  for  some  time  after  birth  is  milk  prepared  from  the  blood 
of  the  mother,  and  this  is  the  most  complete  food  known. 

The  milk  is  secreted  by  the  mammary  glands  which  begin  to 
swell  and  become  active  even  before  the  young  are  born,  and  in 
healthy  animals  continue  to  give  enough  milk  to  feed  the  young 
animals  until  they  are  large  and  strong  enough  to  be  weaned. 
It  is  a  striking  fact  that  there  is  very  little  in  the  anatomy  or  the 
habits  of  the  lower  vertebrates  to  give  a  clue  to  the  origin  of  the 
milk  glands  which  all  mammals  possess,  or  of  the  habit  of  feeding 
the  young  by  a  secretion  from  the  skin  of  the  mother.  The  skin 

183 


1 84  CHILDHOOD  OF  ANIMALS 

of  most  fishes  secretes  an  abundant  mucus  from  little  glands  some- 
times opening  directly  on  the  surface,  sometimes  into  a  set  of 
canals  on  the  head  and  sides  of  the  body.  The  secretion  no  doubt 
helps  to  keep  the  skin  smooth  and  soft  and  more  fit  to  glide  through 
the  water,  and  is  also  useful  in  washing  off  the  spores  of  moulds 
and  fungi  and  other  harmful  parasites  which  might  otherwise  settle 
on  the  body.  It  may  also  be  protective  by  being  offensive  to  other 
animals.  Living  fish  which  have  been  captured  and  put  in  a 
bucket  of  water  usually  discharge  large  quantities  of  mucus  ;  two 
or  three  hagfish  put  in  a  bucket  may  give  oft  so  much  that  the 
sea- water  almost  sets  in  a  jelly.  Frogs,  toads  and  newts  also  give 
off  an  abundant  slime  which,  besides  its  other  useful  properties, 
certainly  has  an  offensive  taste  and  protects  them  from  being 
swallowed  by  many  animals.  A  dog  will  not  try  to  eat  a  frog  or 
toad  twice.  In  reptiles  the  skin  glands  are  not  so  profusely 
scattered  over  the  body  ;  they  are  larger  and  arranged  in  definite 
places,  and  the  skin  as  a  whole  is  dry.  Why  so  many  persons 
believe  that  serpents  are  slimy  I  do  not  know  ;  their  skin  is  always 
absolutely  dry.  In  lizards  there  are  usually  rows  of  skin  glands 
along  the  inner  side  of  the  thighs  ;  in  turtles  and  tortoises  on  the 
soft  skin  between  the  junction  of  the  upper  and  lower  "  shells/' 
and  sometimes  under  the  chin.  Crocodiles  have  large  skin  glands 
on  the  lower  jaw,  and  snakes  near  the  anus,  whilst  in  some  there 
are  smaller  glands  near  the  edges  of  the  mouth.  It  is  certain  in 
some  cases  and  probable  in  others  that  the  secretions  of  these 
large  glands  have  a  strong  odour,  often  musky  or  disagreeable 
and  often  discharged  when  the  animal  is  annoyed,  as  in  the  well- 
known  case  of  the  common  English  grass  snake.  In  birds  the 
skin  generally  is  not  glandular.  There  is  a  very  large  gland,  the 
preen  gland  on  the  back,  with  a  nipple  from  which  an  oily  secretion 
is  discharged,  which  the  bird  smears  on  its  beak  and  uses  to 
preen  the  feathers.  In  some  of  the  aquatic  birds  there  is  a  pair 
of  glands  on  the  lower  jaw. 

These  various  glands  are  protective,  or  odoriferous,  and  may 
advertise  the  presence  of  their  owners  at  the  breeding  time,  but  in 
no  case  is  their  secretion  employed  to  feed  the  young.  In  mammals 
there  are  various  masses  of  skin  glands  secreting  odoriferous 
substances  in  different  parts  of  the  body  :  on  the  feet  of  ruminants, 
on  the  legs  of  horses,  on  the  fore-arms  of  lemurs,  on  the  tails  of  dogs 
and  wolves,  on  the  backs  of  peccaries  and  hyraces,  on  the  faces 
of  antelopes  and  deer,  on  the  temple  of  elephants,  near  the  anus 


THE  FOOD  OF  YOUNG  ANIMALS  185 

of  carnivores,  and  in  many  other  situations,  and  it  is  these  which 
may  be  most  easily  compared  with  the  special  glands  of  reptiles. 
Mammals  have  also  two  kinds  of  skin  glands  not  found  in  other 
animals  :  the  sweat  glands  which  pour  out  a  watery  secretion  that 
is  partly  a  waste  product  and  partly  helps  to  regulate  the  tempera- 
ture by  cooling  the  over-heated  skin,  and  the  sebaceous  glands 
which  discharge  an  oily  fluid  at  the  roots  of  the  hairs  which  auto- 
matically keeps  them  soft  and  flexible.  The  milk  glands  of 
all  mammals  *  are  simply  masses  of  much  enlarged  sebaceous 
glands,  and  milk  is  an  oily  fluid  to  be  compared  with  the  ordinary 
sebaceous  fluid.  By  what  stages  this  became  turned  into  milk 
and  used  for  the  feeding  of  the  young  it  is  very  difficult  to  under- 
stand. 

However  they  may  have  come  into  existence,  the  mammary 
glands  of  all  mammals  secrete  milk  in  sufficient  quantities  for  the 
young  and  of  much  the  same  nature  in  every  case.  I  should  have 
said  the  mammary  glands  of  all  female  mammals,  because  although 
the  structures  exist  in  the  males,  they  are  rudimentary,  and  although 
in  some  abnormal  instances  they  may  secrete  a  small  quantity  of 
a  milky  fluid,  the  suckling  of  the  young  is  entirely  the  work  of  the 
females.  The  milk  of  different  mammals  differs  slightly  in  colour, 
taste  and  odour,  but  these  qualities  are  of  little  importance,  and 
just  as  the  flesh  of  all  mammals  consists  of  the  same  kinds  of  sub- 
stances in  slightly  different  proportions,  so  the  only  food  used  to 
build  up  the  flesh  of  young  mammals  consists  of  the  same  kinds  of 
chemical  materials. 

By  far  the  greater  part  of  the  weight  of  the  body  of  an  animal  is 
made  up  of  the  water  its  tissues  contain,  and  so  from  seventy 
to  ninety  per  cent,  of  milk  is  water.  Next  in  importance  come  the 
very  complicated  nitrogenous  substances  known  as  proteins,  of 
which  the  most  familiar  example  is  the  white  of  an  egg.  In  milk 
the  proteins  form  from  one  and  a  half  to  ten  per  cent.,  and  are 
present  as  casein,  the  chief  component  of  the  curd  which  is  formed 
when  acid  is  added,  and  albumin,  which  becomes  solid  when  milk 
is  boiled.  Protein  builds  up  the  vital  framework  of  the  tissues  ; 
muscle,  nerve,  every  living  part  of  the  body  is  simply  living  protein. 
In  a  fully  grown  animal  protein  does  little  more  than  repair  waste, 
and  under  perfectly  healthy  conditions  only  so  much  protein  is 
required  in  the  food  as  is  necessary  to  repair  the  wear  and  tear  of 

*  The  statement,  common  in  text-books,  that  the  mammary  glands  of  mono- 
tremes  are  derived  from  sweat  glands  and  are  therefore  different  from  those  of  all 
other  mammals,  is  erroneous. 


186  CHILDHOOD  OF  ANIMALS 

life.  In  the  young  and  growing  body  a  much  larger  proportion 
of  protein  is  necessary,  as  the  tissues  themselves  are  growing  and 
have  to  be  built  up.  Next  comes  the  fat,  which  rises  to  the  surface 
in  the  form  of  cream,  or  can  be  separated  as  butter.  In  different 
milk  it  varies  in  quantity  from  about  one  per  cent,  to  ten  per  cent, 
and  is  present  in  different  chemical  forms.  Fats  are  used  to  a  very 
small  extent  in  the  actual  building  of  the  framework  of  the  body. 
They  are  burnt  in  the  tissues  to  supply  heat  and  energy.  The  fats 
are  suspended  as  little  globules  in  the  liquid  of  the  milk  and  give 
it  a  white  appearance.  All  milk  contains  sugar  in  proportions 
ranging  from  three  to  seven  per  cent.  Milk  sugar  is  chemically 
different  from  cane  sugar  or  grape  sugar,  and  also  differs  in  different 
animals.  The  sugar  of  mares'  milk,  for  instance,  can  be  fermented; 
producing  alcohol,  and  this  property  is  employed  to  make  weak 
fermented  beverages  such  as  the  well-known  kephir  and  kumiss  of 
the  Caucasus  and  the  Russian  steppes  ;  the  lactose  or  milk  sugar 
of  cows'  milk  does  not  ferment  in  this  way.  The  sugars,  like  the 
fats,  play  little  part  in  the  actual  composition  of  tissues,  but  serve 
as  fuel.  Lastly,  all  milk  contains  a  small  amount  of  dissolved 
mineral  matter,  the  ash  which  is  left  when  it  is  dried  and  burnt, 
and  this  is  practically  the  same  as  the  ash  when  flesh  is  similarly 
treated. 

Although  in  a  general  way  the  milk  of  all  animals  is  similar,  as 
it  has  to  build  up  and  nourish  tissues  which  are  similar,  there  are 
striking  practical  differences.  Unfortunately  we  do  not  know  very 
much  about  the  exact  constitution  and  properties  of  milk  except 
in  a  small  number  of  animals,  but  we  do  know  enough  to  re- 
cognise four  distinct  types  adapted  to  four  types  of  structure. 
I  can  explain  this  best  by  giving  a  Table  which  sets  out  the  main 
facts,  and  then  taking  the  four  groups  in  turn.  In  the  first  column 
I  have  given  the  kinds  of  animals  to  which  the  types  belong.  In 
the  second  and  third  columns  I  have  taken  the  whole  cubical 
capacity  of  the  stomach  and  intestines  at  100  and  set  down  the 
relative  proportions  of  the  stomach  capacity  and  the  intestinal 
capacity.  Next  follows  the  nature  of  the  curdling,  the  kind  of 
change  which  occurs  when  the  milk  is  mixed  with  the  digestive 
fluids  of  the  stomach,  and  in  the  last  four  columns  the  percentages 
of  the  four  chief  substances  of  which  milk  is  composed.  The  Table 
must  not  be  taken  as  an  accurately  worked-out  scientific  statement 
of  the  case,  because  there  is  not  sufficient  knowledge  for  this,  but 
only  as  true  in  a  general  way. 


THE  FOOD  OF  YOUNG  ANIMALS 

Types  of  Milk 


187 


Kind  of  animals 

Total  digestive 
capacity=ioo 

Kind  of 
curdling 

Percentage  of  chief  constituents 

Stomach 

Intes- 
tines 

Water 

Protein 

Fat 

Sugar 

i.  Herbivores          ~\ 

which   chew  the 
cud,  e.g.  cow, 
antelope 

70 

30 

Solid 

85 

4 

4 

5 

2.  Herbivores 

which  do  not 
chew  the  cud, 
e.g.  horse,  rhino- 

10 

90 

Like 
jelly 

90 

2 

I 

7 

ceros 

3.  Man  and  the      \ 
apes  and 
monkeys 

20 

80 

Loose 
and 
lumpy 

88 

1-5 

3-o 

7-5 

4.  Carnivores,  e.g.  \ 
lion,   cat,  dog     / 

70 

30 

Solid 

75 

10 

10 

3 

The  animals  in  the  first  group  are  the  ruminants,  but  they  do 
not  chew  the  cud  during  the  stage  of  their  life  when  they  are  living 
chiefly  on  mother's  milk.  The  capacity  of  the  stomach  and  of  the 
intestines  is  enormous,  but  in  early  life  the  intestines,  and  especially 
the  caecum,  or  capacious  blind  gut,  remain  narrow,  and  the  result 
is  that  the  greater  part  of  the  digestion  takes  place  in  the  stomach. 
The  milk  forms  a  solid  mass  of  curd  when  it  is  acted  on  by  the 
ferments  produced  by  the  wall  of  the  stomach.  The  curd  remains 
five  hours  at  least  in  the  stomach  and  is  not  passed  into  the  intestines 
until  it  is  fully  digested  and  ready  to  be  absorbed. 

Exactly  opposite  conditions  exist  in  the  herbivorous  animals 
which  do  not  chew  the  cud,  such  as  horses  and  tapirs  and  the 
rhinoceros.  In  these  also  the  whole  capacity  of  the  digestive  canal 
is  great,  but  it  is  differently  distributed,  for  even  in  the  young  foal 
the  intestines  are  nearly  nine  times  as  capacious  as  the  stomach. 
The  milk  when  it  is  acted  on  by  the  digestive  juices  forms  a  soft, 
gelatinous  curd  which  passes  very  easily  out  of  the  stomach  into 
the  intestines,  remaining  in  the  former  organ  rather  less  than  two 
hours.  The  chief  work  of  the  digestive  juices  as  well  as  the  absorp- 
tion of  the  digested  material  take  place  in  the  intestines. 


i88  CHILDHOOD  OF  ANIMALS 

In  man  and  the  apes  the  stomach  is  also  very  small  in  proportion 
to  the  capacity  of  the  intestines,  although  not  so  small  as  in  the 
horse  and  rhinoceros.  The  milk  forms  a  very  loose  curd,  broken 
up  into  small  soft  lumps,  when  it  is  acted  on  by  the  digestive  juices, 
and  remains  rather  longer  in  the  stomach  than  in  the  case  of  the 
horse,  but  not  so  long  as  in  the  calf,  and  the  work  of  digestion  is 
shared  rather  equally  by  stomach  and  intestines. 

In  the  carnivores  the  total  capacity  of  the  digestive  tract  is 
small,  but  the  stomach,  just  as  in  the  calf,  is  more  than  twice  as 
capacious  as  the  intestines.  The  milk  forms  a  very  dense  and  solid 
curd,  which,  also  as  in  the  calf,  cannot  possibly  pass  into  the  intes- 
tines until  it  has  been  dissolved  by  the  digestive  juices.  And  so 
it  remains  for  a  long  time,  about  five  hours,  in  the  stomach,  and 
is  nearly  ready  to  be  absorbed  when  it  passes  into  the  intestines. 

There  is  nothing  more  important  in  the  feeding  of  all  animals, 
young  or  old,  than  not  to  put  fresh  food  into  the  stomach  until  it 
has  passed  the  last  meal  into  the  intestines,  and  still  better  until 
it  has  had  a  rest  after  being  emptied.  Under  natural  circumstances, 
when  both  the  mother  and  young  are  healthy,  there  is  little  need 
to  attempt  to  regulate  this.  The  quantity  of  milk  secreted  by  the 
mother  and  the  rate  at  which  it  is  formed  supply  more  or  less  the 
right  amounts  for  the  wants  of  the  young,  and  there  is  a  good  deal 
of  natural  elasticity  as  to  quantities.  Few  young  animals,  left  to 
themselves,  will  take  too  much  milk  at  a  time  ;  if  they  happen 
to  do  so,  they  get  rid  of  it  by  the  simple  method  of  throwing  it  up  ; 
the  overloaded  stomach,  as  it  churns  the  milk,  cannot  press  it  into 
the  intestines  and  so  forces  it  back  into  the  mouth.  Even  when 
animals  are  being  fed  artificially,  there  is  not  much  danger  in  giving 
them  too  much  at  a  time  ;  very  little  observation  will  show  the 
quantity  they  can  conveniently  retain,  and  they  should  be  allowed 
to  take  this,  if  it  be  certain  that  the  proper  time  has  elapsed 
since  the  last  meal.  Nature  also  regulates  the  intervals  between 
meals  rather  well.  The  restless  feeling  of  hunger,  which  drives  an 
animal  to  move  about  until  it  finds  the  nipple,  starts  from  the 
stomach,  and  under  healthy  conditions  only  from  a  stomach  which 
has  been  empty  for  some  little  time.  In  artificial  feeding,  the  hours 
should  be  carefully  fixed.  In  the  case  of  horses,  and  the  other 
members  of  the  second  group  where  digestion  is  chiefly  intestinal 
and  the  stomach  is  small,  two  hours  is  a  proper  interval  between 
meals,  with  a  rather  longer  rest  once  a  day,  preferably  at  night. 
In  the  case  of  man  and  monkeys,  the  interval  should  be  from  three 


THE  FOOD  OF  YOUNG  ANIMALS  189 

to  four  hours,  and  in  the  case  of  ruminants  and  carnivores  at  least 
five  to  six  hours.  These  intervals  apply  to  quite  young  animals, 
living  only  on  milk  ;  when  they  are  older,  and  especially  when  other 
substances  are  added  to  the  diet,  the  intervals  may  be  made  still 
longer.  The  important  point  to  remember  is  that  it  is  far  better 
to  give  too  long  an  interval  than  too  short  a  rest  between  meals. 
In  artificial  feeding  of  young  mammals,  it  is  extremely  necessary 
that  each  meal  should  be  given  from  perfectly  fresh  and  clean 
vessels,  as  the  young  are  most  sensitive  to  the  slightest  trace  of 
putrefaction.  It  is  also  useful,  at  least  until  the  animals  are  fairly 
strong  and  active,  to  give  the  milk  as  hot  as  they  can  take  it  without 
being  scalded.  There  are  many  forms  of  feeding  bottles  and  arti- 
ficial nipples  used  for  young  animals,  but  it  is  really  preferable  to 
feed  them  with  a  spoon,  an  egg-spoon  for  very  tiny  things,  and  a 
large  kitchen  spoon  for  larger  animals.  Spoon-feeding  can  be 
made  much  more  sanitary,  as  an  open  implement  can  be  dis- 
infected thoroughly,  and  it  is  more  easy  to  regulate  the  quantity 
and  to  prevent  an  eager  little  creature  from  choking  than  if  it  be 
given  a  nipple.  It  is  surprising  how  quickly  almost  any  kind  of  little 
mammal  learns  to  be  handled  at  feeding  time,  and  to  assist  by 
opening  its  mouth  for  each  spoonful.  Moreover  this  method 
establishes  a  relation  of  confidence  between  the  young  animal  and 
its  guardian  which  is  often  of  the  greatest  use  in  case  of  sickness. 
A  small  sick  mammal  often  refuses  to  eat  and  still  more  to  take 
medicine,  and  if  it  is  unaccustomed  to  be  hand-fed,  the  struggle  to 
make  it  swallow  is  difficult  and  dangerous.  If  it  has  become 
accustomed  to  have  a  towel  put  round  it  (a  process  that  at  first 
frightens  most  older  animals  very  much  indeed),  to  have  its  mouth 
opened  and  a  spoon  used,  it  will  submit  to  this  even  when  it  is 
well  grown  and  capable  of  making  a  serious  fight.  Not  only  can 
it  be  fed,  but  many  little  operations  such  as  cutting  claws,  removing 
milk-teeth,  or  applying  disinfectants  can  be  carried  out  without 
binding  or  gagging,  which,  however  skilfully  performed,  always 
upset  the  patient. 

The  four  columns  on  the  right  of  the  Table  show  the  relative 
proportions  of  the  chief  substances  in  milk  only  in  a  very  general 
way.  There  are  important  minor  differences  in  the  nature 
of  the  proteins,  fats  and  sugars  not  only  between  the  different 
types  but  between  the  milks  of  different  animals  in  the  same  type, 
and  there  is  no  doubt  but  that  its  natural  milk  is  the  best  food  for 
any  animal.  In  cases  of  artificial  feeding,  however,  this  is  usually 


I9o  CHILDHOOD  OF  ANIMALS 

impossible,  and  fortunately  young  animals  are  sufficiently  adaptable 
to  make  it  possible  to  rear  them  on  milk  of  another  type  than  their 
own,  if  a  rough  correction  of  proportions  be  made. 

Cows'  milk  is  usually  the  most  easy  to  obtain,  and  it  will  serve 
in  an  unchanged  form  for  any  of  the  ruminant  herbivorous  creatures, 
although  in  practice  it  is  often  diluted  with  hot  water,  especially 
for  deer.  It  is  not  suitable  for  horses,  tapirs,  or  rhinoceroses,  in 
two  ways.  In  the  first  place  it  contains  twice  the  right  proportion 
of  protein,  much  too  much  fat  and  not  nearly  enough  sugar ;  and 
in  the  next  place  the  solid  curd  that  it  forms  will  not  pass  sufficiently 
quickly  out  of  the  stomach.  Two  of  these  defects  may  be  put  right 
by  one  change.  If  rather  less  than  its  own  bulk  of  very  thin  barley- 
water  be  added,  then  the  proportion  of  protein  will  be  nearly 
right,  and  the  mixture,  instead  of  forming  a  solid  mass  of  curd  in 
the  stomach,  will  remain  in  a  liquid  state  so  that  it  can  pass  at  the 
proper  time  into  the  intestines.  There  will  still  be  too  much  fat, 
but  this  is  of  little  importance,  and  can  easily  be  remedied,  if  thought 
better,  by  skimming  off  a  little  of  the  cream  before  the  mixture 
is  made.  It  will  contain  far  too  little  sugar,  and  a  heaped  tea- 
spoonful  should  be  added  for  each  pint  of  the  mixture. 

The  adaptation  of  cows'  milk  for  the  infants  of  human  beings  or 
monkeys  is  more  complicated.  To  break  up  the  curd,  it  should  be 
diluted  with  a  little  more  than  its  own  bulk  of  thin  barley-gruel 
made  with  malted  barley.  This  will  make  the  proportion  of  protein 
nearly  right,  but  will  reduce  the  fat  far  too  much  and  the  sugar  still 
more.  A  small  teaspoonful  of  cream  and  a  good  teaspoonful  of 
sugar  should  be  added  to  about  the  quantity  of  the  mixture  that 
would  fill  a  large  teacup. 

Probably  because  we  are  accustomed  to  see  cows'  milk  diluted 
when  it  is  being  prepared  for  babies,  most  persons  are  naturally 
inclined  to  add  water  to  it  for  carnivores  such  as  kittens  and  puppies. 
This  is  quite  wrong.  In  the  first  place  the  stomachs  of  these 
animals  are  adapted  for  digesting  a  solid  curd,  and  the  dilution 
of  the  milk  would  prevent  this.  Next,  the  milk  of  carnivores  is 
excessively  rich  in  proteins  and  in  fats,  and  it  is  necessary  to 
strengthen  cows'  milk  to  make  it  suitable.  One  of  the  simplest 
ways  of  preparing  milk  for  carnivores  is  to  add  to  each  teacupful  of 
cows'  milk  a  good  teaspoonful  of  condensed  unsweetened  milk, 
and  a  similar  quantity  of  cream  or  of  olive  oil. 

When  cows'  milk  is  not  available,  or  when,  as  sometimes  happens, 
young  animals  are  not  thriving  on  a  mixture  made  up  from  it, 


THE  FOOD  OF  YOUNG  ANIMALS  191 

there  are  many  useful  brands  of  condensed  milk  which  can  be 
employed.  Those  which  are  unsweetened  are  most  easy  to  work 
with,  and  the  well-known  "  Ideal  "  brand  serves  well.  If  Ideal 
milk  be  diluted  with  nearly  twice  its  bulk  of  plain  warm  water,  it 
will  contain  fairly  exactly  the  right  proportions  of  proteins,  fats 
and  sugar  for  ruminating  herbivores.  To  use  it  for  animals  like 
the  horse,  rhinoceros  and  tapir,  it  should  be  diluted  with  not  quite 
four  times  its  bulk  of  thin  barley-water,  and  will  then  be  nearly 
correct  so  far  as  proteins  go,  but  some  sugar  should  be  added.  It 
will  still  contain  a  slight  excess  of  fat,  but  this  is  of  little  importance 
and  may  be  neglected.  To  prepare  it  for  young  monkeys,  it  should 
be  diluted  with  rather  more  than  four  times  its  bulk  of  barley- 
water,  which  will  bring  the  protein  nearly  right  and  the  fat  almost 
exactly  right,  but  sugar  must  be  added.  To  prepare  it  for  carni- 
vores, a  very  little  warm  water  should  be  added,  not  more  than  just 
enough  to  make  it  possible  to  feed  the  animal  with  it.  It  will 
contain  too  much  sugar,  but  this  may  be  neglected,  and  not  quite 
enough  protein,  which  may  be  easily  put  right  by  adding  a  squeeze 
of  raw  meat  juice. 

The  milk  of  individual  animals  of  the  same  species  varies  so  much 
that  very  exact  measurements  of  the  proportions  of  the  different 
substances  are  not  worth  the  trouble  of  making.  The  really  neces- 
sary things  to  observe  are  the  proper  intervals  between  feeding  for 
the  different  types  of  animals,  and  the  proper  dilution  or  enriching 
of  the  milk,  the  warming  of  it  before  giving  it  while  the  animals 
are  very  young,  and  the  most  scrupulous  cleanliness  and  fresh- 
ness of  everything  used.  If  it  be  at  all  possible,  not  more  than 
enough  for  one  meal  should  be  mixed  at  one  time,  and  all  the  waste 
should  be  thrown  away,  and  a  fresh  start  made  for  the  next  meal. 
More  young  animals  are  lost  from  neglect  of  these  precautions  than 
jfrom  any  inexactness  in  the  proportions  or  quantities  used. 

All  young  mammals  pass  gradually  from  a  milk  diet  to  the 
ordinary  food  of  their  kind,  and  under  natural  conditions  the 
process  of  weaning  is  not  abrupt.  Young  carnivores  begin  to  pick 
at  scraps  from  the  prey  of  the  parents  almost  as  soon  as  their  eyes 
are  open  and  they  are  able  to  move  about  freely.  When  they  are 
being  reared  by  hand,  they  should  be  given  raw  meat  as  soon  as 
they  will  take  it  freely,  and  the  mistake  of  keeping  them  from  it 
too  long  is  made  more  often  than  that  of  giving  it  to  them  too  soon. 
The  cubs  and  kittens  of  all  the  cats,  from  the  lion  down  to  the 
smallest  wild  cat,  can  digest  raw  meat  very  soon,  and  if  they  have 


I92  CHILDHOOD  OF  ANIMALS 

been  kept  on  milk  slops,  scraps  of  cooked  meat  with  gravy  and 
vegetables  and  so  forth,  and  are  not  doing  well,  a  complete  change 
to  raw  meat  is  almost  miraculous  in  its  rapid  effect.     The  meat 
should  be  quite  fresh,  and  it  is  better  to  change  it,  small  rabbits, 
sparrows  and  so  forth  alternating  with  beef,  mutton  or  horse-flesh. 
When  the  larger  kinds  of  meat  are  given,  bones  with  strips  of  flesh 
attached  are  the  most  suitable  form,  as  although  bolting  food  does 
them  no  harm,  it  is  good  that  they  should  exercise  their  teeth  and 
jaws.     I  have  no  doubt  but  that  all  the  cats,  wolves,  foxes,  and 
even  the  domestic  dogs  should  be  put  on  a  raw  meat  diet  as  soon 
as  possible,  and  that  they  do  best  if  they  are  kept  on  it.     When 
they  are  quite  small,  a  meal  twice  or  even  three  times  a  day,  with 
at  least  six  hours'  interval,  is  advisable,  but  later  on  it  should  be 
reduced  to  two  meals  and  finally  to  one  meal  a  day.     It  is  the 
natural  instinct  of  these  animals  to  growl  and  snarl  over  their 
food,  and  it  is  extremely  bad  for  their  health  and  temper  to  tease 
and  disturb  them  while  they  are  eating.     However  savage  they 
may  have  seemed  to  be,  if  they  are  left  in  peace  they  will  come 
to  their  friends  immediately  afterwards  and  sit  down  and  wash 
their  faces  and  paws  peacefully.     The  chief  danger  with  uncooked 
meat  is  infection  from  parasitic  worms,  which  seems  hardly  possible 
to  avoid  even  by   the   most   careful   selection  of  the  food  given. 
The   animals   should   be   watched   carefully  and   their   droppings 
examined  daily,  and  when  there  is  need  they  should  be  starved 
fpr  twenty-four  hours  and  then  given  a  strong  vermifuge,  fed  in  the 
usual  way   for   two   or   three  days,  and  then  the  starving    and 
drug  repeated. 

Apes  and  monkeys  suckle  for  a  long  time  and  the  change  to 
ordinary  food  is  gradual.  Young  monkeys  have  been  observed 
very  little  in  their  natural  surroundings,  but  as  the  parents  do  not 
seem  to  bring  food  to  them,  they  probably  have  to  begin  by  nibbling 
rough  shoots  and  leaves,  and  probably  most  of  them  take  grubs 
and  insects  and  even  young  birds  and  eggs.  In  captivity  they  are 
dainty  creatures,  and  it  is  even  more  important  than  with  children 
not  to  pamper  them.  If  they  are  given  nothing  but  carefully 
cooked  cereals,  white  bread  and  cultivated  fruits  when  they 
first  begin  to  eat,  they  will  refuse  rougher  and  more  wholesome 
food.  The  digestive  organs  of  monkeys  are  more  capacious  than  those 
of  man,  in  proportion  to  their  size,  and  the  greedy  animals  will  eat 
until  they  can  eat  no  more.  Their  food  should  contain  plenty 
of  "  packing/'  that  is  to  say,  it  should  not  be  too  nutritious  in 


THE  FOOD  OF  YOUNG  ANIMALS  193 

proportion  to  its  bulk.  Boiled  potatoes,  wholemeal  bread,  rather 
hard  apples,  vegetables  with  plenty  of  fibre  in  them,  should  form 
the  bulk  of  their  food,  but  they  will  not  take  such  things  if  they  are 
accustomed  to  grapes  and  ripe  bananas,  sweet  biscuits  and  carefully 
prepared  milk  puddings.  Young  monkeys,  even  more  than  young 
carnivores,  should  be  accustomed  to  have  their  mouths  opened, 
and  to  be  fed  with  a  spoon.  They  are  delicate,  even  when  they  are 
not  shut  up  in  a  warmed  house  and  allowed  free  access  to  the  open 
air  in  all  weathers,  and  one  of  the  first  symptoms  of  illness  is  the 
refusal  of  food.  They  are  almost  as  difficult  to  feed  forcibly  without 
doing  them  damage  as  are  hysterical  women,  unless'  they  are 
thoroughly  accustomed  to  being  handled. 

Young  herbivorous  animals  of  all  kinds  begin  to  pick  at  any 
kind  of  vegetable  food  in  a  few  days,  although  they  may  continue 
to  suck  for  months,  or  even  years,  until  the  mother  ceases  to  give 
milk.  In  captivity  they  should  be  encouraged  to  eat,  but  dry 
foods  of  all  kinds,  especially  dried  leaves  and  clover,  are  most  whole- 
some for  them.  If  they  are  being  hand-reared,  however,  they 
should  not  have  free  access  to  such  food  at  all  times  until  they  have 
begun  to  ruminate,  but  small  quantities  should  be  given  them 
instead  of  one  of  their  milk  meals,  and  cleared  away  after  a  quarter 
of  an  hour,  or  given  immediately  before  a  meal  and  similarly  cleared 
away.  For  that  reason  it  is  better  to  keep  them  on  a  litter  such  as 
peat-moss,  which  they  will  not  nibble,  than  on  soft  hay  or  straw. 

The  appetites  of  all  young  animals  are  very  capricious  if  they 
are  not  thriving,  and  unless  they  have  been  accustomed  to  hand- 
feeding,  they  must  be  tempted  in  all  sorts  of  ways,  with  all  sorts  of 
flavours,  before  the  last  expedient  of  forcibly  cramming  them  is 
adopted.  Quite  a  surprising  number  of  different  kinds  of  little 
mammals  can  be  persuaded,  if  some  one  sits  down  patiently  beside 
them  and  makes  sucking  and  chewing  noises  and  pretends  to  eat 
the  food.  Monkeys  are  so  like  human  beings  that  this  device  is 
quite  naturally  successful  in  many  cases.  But  I  have  used  it  myself 
successfully  with  a  caracal  cub,  a  little  hyrax,  a  bear  cub,  a  puppy 
and  a  young  rabbit,  and  seen  it  employed  with  many  other  kinds 
of  animals.  The  most  successful  person  I  have  ever  seen  in  in- 
ducing creatures  to  eat  was  an  ignorant  Irish  peasant  woman, 
who  treated  them  all  as  human  infants,  coaxing  them,  scolding 
them  and  petting  them.  The  great  matter  is  to  get  them  to  eat 
anything  first,  and  then  gradually  to  change  them  to  a  proper  diet. 
All  sorts  of  unexpected  flavours  are  occasionally  relished  by  animals. 

C.A.  N 


I94  CHILDHOOD  OF  ANIMALS 

A  young  orang,  which  had  refused  all  food,  was  tempted  to  eat  and 
brought  back  to  normal  food  and  health  on  several  occasions  by 
flavouring  its  milk  with  stewed  rhubarb.  A  caracal  kitten  in 
my  possession  liked  the  flavour  of  plum-tart  excessively  and 
would  take  milk  with  this  when  it  would  touch  nothing  else. 
A  very  young  tree-hyrax  was  brought  to  me  by  a  young  engineer 
who  had  obtained  it  in  Nigeria  and  was  unaware  of  its  natural  food. 
Deciding  that  it  might  as  well  die  from  improper  food  as  from  starva- 
tion, and  that,  in  any  event,  he  would  give  it  a  chance,  he  succeeded 
by  persuasion  and  force  in  getting  it  to  take  food  which  kept  it  alive, 
but  was  certainly  unnatural.  When  I  took  it  over,  I  could  not  induce 
it  for  some  time  to  eat  what  I  thought  proper,  but  it  took  a  fancy  to 
sponge-fingers  dipped  in  hot  coffee  and  milk,  from  that  passed  to 
strips  of  toast  sopped  in  hot  milk,  which  it  would  take  only  from  the 
hand,  and  then  gradually  learned  to  eat  green  leaves.  But  I  had  to 
try  many  different  kinds,  until  I  found  what  it  would  always  take  ; 
its  favourite  was  hawthorn  and  next  a  very  succulent  grass.  It 
was  given  on  one  occasion  bread  sopped  in  claret  and  liked  that 
immensely,  but  could  not  be  induced  to  touch  bread  if  dipped  into 
moselle,  or  port,  or  champagne.  It  was  extremely  fond  of  ice 
wafers,  but  took  no  special  interest  in  them  unless  they  were  those 
of  a  particular  maker.  The  young  elephant-seal  in  the  London 
Zoological  Gardens,  which  ought  to  be  purely  a  fish-eater,  acquired 
so  voracious  an  appetite  for  buns  that  the  public  had  to  be  warned 
against  feeding  it.  Once  in  the  absence  of  the  proper  official  I 
had  to  try  to  give  a  young  bear  a  dose  of  castor  oil.  After  half  an 
hour's  struggle,  in  which  the  keeper  and  I  both  got  scratched  and 
bitten  and  had  our  coats  torn,  we  succeeded  in  forcing  perhaps  half 
a  teaspoonful  down  its  throat.  We  gave  it  up,  and  as  a  last  chance 
I  poured  some  out  in  a  dish  and  left  it  in  front  of  the  bear,  which  at 
once  rushed  at  it,  and  greedily  drank  it  all  up.  Patience  and 
experiment  are  the  most  successful  methods  with  all  animals. 
|  I  have  already  spoken  of  the  care  given  by  birds  to  the  feeding  of 
the  young.  In  the  brush  turkeys,  probably  alone  among  birds,  it 
does  not  occur,  but  the  full-fledged  chicks  look  after  themselves 
as  soon  as  they  are  hatched.  In  the  birds  that  are  hatched  in 
'a  downy  and  active  condition,  the  parents  may  actually  bring 
food,  or  may  only  call  the  attention  of  the  young  to  food  they 
'scratch  up. 

In  ducks  and  geese  the  young  are  taken  to  food  rather  than 
actually  fed.    In  the  vast  army  of  birds  which  are  hatched  in  a 


THE  FOOD  OF  YOUNG  ANIMALS  195 

helpless  condition,  the  young  are  fed  from  the  beginning.  Since 
the  young  of  birds  are  either  fed  or  watched  by  the  parents,  they 
have  the  racial  habit  of  confidence,  and  the  new-hatched  young 
or  the  fledglings  of  even  the  shyest  or  fiercest  of  birds  are  all  perfectly 
ready  to  be  fed  by  human  beings,  and  only  acquire  their  dread  of 
man  when  they  are  grown  up.  All  that  is  necessary  is  to  know 
their  habits,  or  to  find  out  by  experiment  whether  the  food  must  be 
thrown  down  for  them  to  pick  up  or  actually  put  into  their  mouths, 
and  they  themselves  assist  by  showing  what  they  want.  Most 
birds  that  are  hatched  in  a  nearly  naked  condition  must  have  the 
food  put  in  their  mouths,  and  this  applies  also  to  most  shore-birds 
and  aquatic  birds,  whilst  most  of  the  ground-birds  and  game-birds 
pick  it  up  for  themselves. 

I  do  not  know  of  any  instances  in  which  the  young  of  reptiles 
are  actually  fed  by  their  parents.  They  are  hatched  or  born  in  an 
active  condition,  and  very  quickly  begin  to  eat  on  their  own  account. 
By  far  the  greatest  number  of  them  are  carnivorous,  and  when 
they  are  small  should  be  supplied  with  worms  or  grubs,  very 
small  fish  or  frogs,  or  strips  of  meat  cut  into  worm-like  shapes,  or 
eggs  broken  open  or  even  hard  boiled  and  broken  up.  A  few  of 
the  lizards  and  the  land  tortoises  are  vegetarian  and  will  eat  fruit, 
berries,  lettuce  and  other  green  food,  but  even  these  will  take  also 
slugs  and  grubs,  particularly  when  they  are  young. 

Reptiles  are  rather  capricious  feeders,  especially  in  captivity,  and 
the  difficulty  is  the  greater  because  they  all  are  able  to  fast  for  very 
long  periods  without  coming  to  harm,  and  it  is  not  easy  to  know 
at  what  point  it  is  necessary  to  take  active  steps  to  make  them 
feed.  It  is  certain,  however,  that  young  reptiles,  like  any  other 
young  animals,  cannot  abstain  from  food  for  so  long  as  fully  grown 
animals ;  and  especially  when  winter  is  approaching,  a  time  when 
,the  natural  vitality  of  reptiles  is  at  an  ebb,  it  is  necessary  to  see 
that  they  begin  their  usually  long  fast  with  some  good  meals. 
The  vegetable  feeders  should  be  tempted  with  as  many  different 
kinds  of  green  food  as  can  be  obtained,  until  something  that  they 
will  take  is  found.  Green  leaves  of  clover  are  taken  most  readily 
by  small  tortoises,  and  pieces  of  banana  by  vegetarian  lizards. 
A  friend  of  mine  told  me  that  he  had  found  out  that  if  an  obdurate 
tortoise  were  put  on  its  back,  when  it  struggled  to  the  right  position 
again  it  seemed  to  have  been  so  surprised  that  it  forgot  its 
former  unwillingness  and  meekly  began  to  feed  at  once.  I  have 
tried  this  device  myself,  but  with  very  infrequent  success.  Small 


196  CHILDHOOD  OF  ANIMALS 

alligators  and  crocodiles,  and  many  little  snakes  and  water-tortoises 
are  most  readily  tempted  by  small  fish,  other  snakes  and  lizards 
by  small  frogs,  and  chameleons  by  mealworms. 

The  surest  device,  however,  is  to  warm  the  little  reptiles  well 
before  trying  to  feed  them.  Little  alligators  and  crocodiles,  small 
water-tortoises  and  many  little  snakes  will  usually  feed  readily  if 
put  first  in  a  bowl  of  water  heated  to  a  temperature  of  about 
100°  Fahr.,  and  snakes  and  lizards  and  land  tortoises  should  be  put 
in  front  of  a  hot  fire  (with,  of  course,  the  chance  of  wriggling  away  if 
they  find  it  too  hot)  or  taken  into  the  hottest  compartment  of  a 
greenhouse.  In  the  first  winter  of  their  life  they  should  be  wakened 
up  by  this  method  and  offered  food  at  least  once  a  week.  When 
they  are  older,  if  they  have  been  well  fed  through  the  autumn  and 
are  plump  and  heavy,  they  need  not  be  disturbed. 

If  natural  methods  fail,  cramming  may  be  readily  carried  out  with 
most  reptiles,  and  is  sometimes  successful.  It  is  comparatively  easy, 
because  the  gullet  is  wide  and  runs  straight  back  to  the  stomach 
from  the  line  of  the  floor  of  the  mouth,  and  there  is  little  danger, 
if  use  be  made'  of  a  blunt  instrument  incapable  of  doing  damage 
to  the  back  of  the  mouth  and  throat.  Young  crocodiles,  alligators, 
turtles  or  lizards  should  be  held  firmly  with  the  left  hand  and 
gently  tickled  along  the  soft  skin  near  the  hinge  of  the  upper  and 
lower  jaws  until  they  gape,  when  a  bolus  of  meat  can  easily  be  placed 
far  back  in  the  mouth  and  pushed  down  the  throat.  Snakes  have 
to  be  handled  more  gently,  partly  because  their  ribs  are  very  easily 
broken  when  they  struggle,  and  partly  because  if  they  wriggle,  the 
rather  long  gullet  may  not  be  straight  and  its  wall  be  damaged. 
I  once  saw  a  twenty-foot  python  being  stuffed  in  a  foreign  Zoological 
Collection.  Its  own  keeper  seized  hold  of  it  just  behind  the  head 
and  pulled  it  out  of  its  cage  coil  by  coil,  whilst  a  set  of  assistants 
took  their  stations  behind  him,  each  grasping  firmly  a  successive 
portion  of  the  snake  as  it  was  handed  out.  Finally,  nine  or  ten 
keepers  in  a  row  were  holding  the  python  and  had  much  ado  to 
keep  it  straight.  The  food,  which  consisted  of  four  skinned  rabbits 
arranged  like  a  sausage  on  a  long  pole,  had  been  prepared  before- 
hand. The  keeper  at  the  head  then  opened  the  jaws  of  the  snake, 
and  a  waiting  expert  slowly  pushed  the  pole  with  the  rabbits  down 
the  throat  of  the  snake  until  he  had  got  it  quite  home.  The  pole 
was  then  slowly  withdrawn,  and  the  rabbits  were  left  behind,  and 
the  mouth  of  the  snake  was  cleaned  and  disinfected.  The  last 
stage  of  the  operation  was  to  buckle  a  leather  strap  rather  tightly 


THE  FOOD  OF  YOUNG  ANIMALS  197 

round  the  neck  of  the  python,  as  otherwise  it  might  have  disgorged 
the  food  that  it  had  been  compelled  to  take. 

Cramming  is  not  much  in  favour  with  those  who  are  experts  in 
keeping  reptiles,  and  it  is  alleged  that  very  frequently  stuffed 
animals  fail  to  digest  their  meal  and  die  as  the  result  of  it.  It 
certainly  is  the  case  that  the  imperfectly  digested  remains  of  such 
a  meal  are  frequently  found  in  post-mortem  examinations,  but  the 
argument  is  not  quite  complete,  because  snakes  that  refuse  their 
food  and  have  to  be  forcibly  fed  are  usually  in  an  unhealthy  con- 
dition. 

This  raises  the  very  interesting  and  difficult  question  as  to  the 
giving  of  a  living  prey  to  reptiles  in  captivity.  The  Buddhist 
standpoint  may  be  taken,  and  those  who  are  of  the  opinion  that 
it  is  wrong  under  any  circumstances  to  procure  or  connive  at  the 
extinction  of  life  may  go  the  extreme  length  of  refusing  to  give 
mealworms  or  cockroaches  to  lizards,  or  worms  and  little  fishes 
and  frogs  to  alligators  and  snakes.  For  most  persons,  however, 
the  doubtful  point  comes  when  it  is  a  question,  not  of  giving  small 
and  unintelligent  creatures  to  animals  that  will  bolt  them  whole 
and  certainly  kill  them  as  instantaneously  as  can  be  done,  but 
of  giving  birds  and  mammals  to  large  snakes.  The  problem,  there- 
fore, fortunately  does  not  arise  with  very  young  snakes,  but  as 
it  is  interesting  and  as  I  have  given  special  attention  to  it,  I  may 
digress  to  discuss  it. 

The  large  poisonous  snakes  when  they  are  restless  and  show 
that  they  are  hungry  generally  dart  at  their  prey  as  soon  as  it 
is  put  in  the  cage,  strike  at  it,  inject  the  poison  from  their  poison 
fangs  with  the  rapidity  of  lightning  and  then  withdraw  and  wait 
for  some  time  before  they  proceed  to  swallow  it.  The  victim  dies 
very  quickly,  as  quickly  as  it  can  be  killed  by  almost  any  method, 
and,  so  far  as  it  is  possible  to  judge  from  its  behaviour,  painlessly. 
So  also  when  a  constricting  snake,  like  a  python  or  anaconda, 
is  really  hungry,  and  the  expert  keeper  can  almost  unfailingly 
recognise  that  condition,  it  strikes  almost  at  once  at  the  prey, 
seizing  it  with  its  mouth,  and  with  an  indescribably  rapid  move- 
ment throws  one  or  two  heavy  loops  of  its  body  over  it  and 
crushes  it.  If  the  animal  struggles,  further  coils  are  thrown  over, 
and  in  a  very  short  time  the  creature  is  smothered.  Even  if  it 
showed  signs  of  being  hungry,  the  snake  generally  waits  some 
time  before  beginning  the  long  process  of  swallowing  the  prey, 
which  is  always  dead  and  sometimes  quite  cold  first.  When  the 


I98  CHILDHOOD  OF  ANIMALS 

snake  is  hungry  and  has  proper  accommodation  to  strike  and 
smother  its  victim,  I  think  the  actual  death  in  this  case,  too,  is 
as  often  painless  as  when  an  animal  is  killed  for  human  food. 

It  is  necessary  to  insist,  however,  on  the  fact  that  in  both  cases 
the  prey  is  extremely  seldom  eaten  for  some  time  after  it  is  dead. 
If  the  mouse  or  rat,  guinea-pig,  duck,  or  goat  has  been  first  killed 
by  the  keeper,  and  thrown  into  the  cage  of  a  really  hungry  snake, 
the  snake,  whether  poisonous  or  a  constrictor,  will  behave  exactly 
as  if  the  victim  were  alive,  will  strike  at  it  and  withdraw  in  the 
one  case,  or  strike  at  it  and  throw  a  coil  over  it  in  the  other  case, 
and  in  time  proceed  to  eat  it  as  if  it  had  not  noticed  the  difference. 
If  the  snake  is  not  very  active  and  has  to  be  excited  or  tempted, 
this  can  very  often  be  done  by  dangling  the  dead  prey  at  the 
end  of  a  pole  or  some  other  simple  mechanical  device.  It  is  my 
personal  opinion  that  in  nearly  every  case  a  snake,  if  it  be  kept 
properly  warm  and  not  fed  except  when  it  is  either  hungry  or 
ought  to  be  hungry,  can  be  induced  to  take  dead  food.  And 
I  have  no  doubt  but  that  it  digests  the  food  which  has  been  killed 
by  a  keeper  just  as  well  as  when  it  has  killed  it  itself.  My  own 
experience  and  observations  have  led  me  to  believe,  against  the 
opinion  of  many  experts,  that  there  is  very  little  in  the  view  that 
the  digestive  secretions  do  not  work  properly  unless  the  snake 
has  had  the  excitement  of  killing  its  own  food.  A  hungry,  healthy 
snake  has  an  excellent  digestion,  and  can  deal  very  well  with 
anything  it  has  swallowed.  I  believe  also  that  there  is  less  than 
nothing  in  the  curious,  half-superstitious  notion  that  living  food 
is  better  for  living  snakes  than  dead  food.  The  small  snakes 
certainly  usually  take  their  food  alive,  but  they  will  take  killed 
food,  if  it  is  fresh,  equally  well,  and  the  large  snakes  always  wait 
until  their  prey  is  dead  before  they  eat  it. 

There  remain,  however,  a  small  number  of  cases  in  which 
individual  snakes  refuse  all  persuasion  and  would  probably  die 
unless  they  are  allowed  to  kill  their  victim.  Such  cases  certainly 
do  occur,  and  those  who  have  to  deal  with  them  must  decide  them 
according  to  their  own  sense  of  what  is  right,  whether  to  let  the 
snake  die  or  to  let  it  kill  its  prey.  Some  years  ago,  to  make  up 
my  own  mind,  I  made  a  number  of  observations  with  my  colleague, 
Mr.  R.  I.  Pocock,  to  ascertain  the  behaviour  of  different  animals  in  the 
presence  of  snakes.  Clearly,  if  animals  are  really  frightened  in  the 
presence  of  snakes,  there  is  much  more  than  the  mere  fact  that  they 
are  killed  and  eaten  to  be  considered  before  we  use  them  as  food, 


THE  FOOD  OF  YOUNG  ANIMALS  199 

especially  if  the  snake  to  be  fed  is  not  very  active  and  does  not 
seize  the  prey  at  once.  The  usual  animals  used  for  food,  besides 
fish,  frogs  and  worms,  are  pigeons,  ducks,  rats,  rabbits,  guinea- 
pigs  and  goats.  I  have  watched,  very  carefully,  what  happens 
when  these  are  put  into  the  cage  of  a  snake  and  are  not  seized  at 
once.  At  first,  just  like  any  animals  put  in  a  strange  place,  they 
look  about  them,  and  if  they  are  not  quite  tame  they  may  bolt 
to  the  darkest  corner.  Presently,  however,  they  become  at  home. 
The  ducks  waddle  about,  the  pigeons  preen  their  feathers,  rats, 
rabbits  and  guinea-pigs  scamper  all  over  the  cage  or  sit  up  and 
wash  themselves,  and  goats  behave  precisely  as  they  do  in  any 
enclosure.  None  of  them  pay  the  slightest  attention  to  the  snake 
if  it  is  merely  lying  quiet,  and  I  have  seen  all  of  them  walk  over 
the  snake  and  lie  down  on  it  or  beside  it  with  complete  unconcern. 
When  the  snake  moves,  they  get  out  of  its  way  or  push  against  it, 
just  as  they  would  do  with  a  stick,  or  another  harmless  animal  of 
the  same  kind.  They  have  no  special  dread  of  snakes,  nor  the 
slightest  instinctive  fear  or  foreknowledge  of  their  approaching 
doom.  We  tried  a  further  set  of  experiments  by  taking  a  large 
tame  snake,  which  was  very  active,  to  the  houses  in  which  various 
animals  were  kept,  and  at  the  Royal  Institution  I  repeated  some 
of  these  experiments  in  public,  by  introducing  various  animals  in 
turn  to  a  snake,  if  they  could  be  taken  out  of  their  cages,  or  by 
holding  the  snake  against  the  cage  in  which  they  were  contained 
and  letting  it  move  over  the  cage  or  even  try  to  get  its  head  through 
the  bars.  The  snake  that  was  used  was  not  a  poisonous  one,  but 
I  should  not  expect  animals  to  notice  a  difference  to  which  very 
few  human  beings  would  pay  any  attention.  A  great  many  different 
ground-birds  and  water-birds  were  tested ;  fowls,  pheasants,  ducks; 
geese,  rails,  coots  and  so  forth  either  paid  no  attention  to  the 
snake  or  tried  to  peck  at  it,  in  the  fashion  that  they  would 
peck  at  any  moving  object.  Parrots  and  cockatoos  were  equally 
indifferent.  A  yellow-crested  cockatoo  which  I  had  at  the  Royal 
Institution  amused  us  by  being  really  frightened  of  a  guinea-pig, 
raising  its  crest  and  making  a  great  fuss,  but  showing  itself  com- 
pletely unconcerned  when  the  snake  writhed  and  twisted  towards 
it.  Some  of  the  more  intelligent  of  the  passerine  birds,  and  in 
especial  an  Indian  hill  mynah,  showed  their  knowledge  and  dread 
of  the  snake  in  the  most  definite  way.  The  mynah's  cage  had  been 
covered  up,  so  that  the  snake  appeared  to  it  quite  suddenly,  and  it 
began  to  shriek  in  an  excited  way  and  darted  up  to  the  remotest  part 


200  CHILDHOOD  OF  ANIMALS 

of  the  cage  with  so  great  a  fear  that  we  had  to  remove  the  snake 
at  once.  Immediately  afterwards  the  bird  came  to  the  bars  and 
pecked  at  my  fingers  in  a  friendly  way,  and  showed  the  same  atten- 
tion to  the  guinea-pig.  It  was  not  a  shy  bird  or  timorous,  but  it 
knew  snakes  and  feared  them. 

Moreover,nearly  every  kind  of  mammal  that  we  tried  was  indifferent 
to  snakes.     Guinea-pigs  and  rats  would  run  over  them ;    a  hyrax, 
which  is  both  intelligent  and  which  from  living  in  trees  and  on 
rocks  must  often  encounter  snakes,  was  hardly  even  interested. 
When  the  snake  touched  it  with  its  tongue,  the  hyrax  moved  back 
suddenly,  just  as  when  some  one  it  did  not  know  touched  it,  but 
immediately  afterwards  stretched  out  and  sniffed  at  the  reptile, 
and  then,  satisfied  that  it  was  not  good  to  eat,  took  no  further 
notice.     Small  carnivores,  dogs,  foxes  and  wolves,  sheep,  antelopes 
and  deer,  zebras  and  donkeys  were  either  quite  indifferent  or  came 
up  to  the  bars  and  sniffed,  and  then,  deciding  that  the  snake  was 
not  a  bun  or  piece  of  sugar,  moved  away  with  an  air  of  wearied 
disgust  at  having  been  deceived.     As  monkeys  are  well  known  to 
recognise  snakes,  we  tried  nearly  every  different  kind  in  the  Zoo- 
logical Gardens.     Lemurs  of  all  kinds  have  no  dread  of  snakes  and 
show  no  trace  of  any  knowledge  of  them.     Without  exception, 
they  all  came  to  the  bars  of  their  cages  expecting  to  be  fed,  and 
tried  to  snap  at  the  snake  as  they  would  at  any  kind  of  food.     The 
small  American  monkeys,  which  are  less  intelligent  than  the  monkeys 
of  the  Old  World,   were  uncertain  in  their  behaviour.     Several 
marmosets,  although  these  are  shy  and  timid  creatures,  and  must 
often  be  the  victims  of  snakes  in  their  native  land,  acted  rather 
like   lemurs,    being   indifferent   or   very   curious.     Capuchins   and 
howlers,  spider  monkeys  and  woolly  monkeys,  however,  nearly  all 
behaved  like  their  Old  World  allies.     And  there  is  doubt  as  to  the 
recognition  of  snakes  by  the  ordinary  macaques  and  cercopitheques, 
the  baboons  and  mandrills.     As  soon  as  a  snake  is  brought  into 
the  monkey-house  there  is  a  great  outcry.      The  first  monkey  that 
sees  it  gives  a  peculiar  scream  and  dashes  off  to  the  highest  and 
furthest  part  of  the  cage,  and  the  others  at  once  come  to  see  what 
is  the  matter,  and  in  turn  dash  away.     From  the  largest  baboon 
down  to  the  smallest  macaque  all  were  equally  frightened  and 
excited.     At  the  Royal  Institution  I  showed  a  snake  successively 
to  a  lemur,  a  very  young  cebus  monkey  and   a   young  Arabian 
baboon.     The  lemur  had   been  born   at  the   London  Zoological 
Gardens  and  probably  had   never  seen  a  snake  until  that  day ; 


THE  FOOD  OF  YOUNG  ANIMALS  201 

the  two  little  monkeys  were  still  very  young,  and  had  come  to 
the  Gardens  when  they  were  such  babies  that  almost  certainly 
they  could  have  had  no  individual  experience  of  snakes.  The 
difference  in  the  behaviour  of  the  lemur  and  the  monkeys  was 
startling.  The  lemur,  like  all  the  others  I  had  tried,  was  almost 
aggressive  in  its  want  of  fear  ;  the  monkeys  were  panic-stricken, 
and  the  snake  had  to  be  removed  at  once. 

The  anthropoid  apes  in  the  Ape  House  at  the  London  Zoological 
Gardens  were  also  tried  with  various  kinds  of  snakes.  The  gibbons 
were  east  timid ;  a  very  small  agile  gibbon  showed  no  fear  and  very 
little  curiosity,  while  a  full-grown  example  of  the  same  species 
and  a  hoolock  gibbon  showed  no  panic,  but  retreated  very  decidedly. 
It  is  possible  that  gibbons,  as  they  are  the  most  agile  and  completely 
arboreal  of  all  the  monkeys,  run  little  risk  from  snakes  and 
have  partly  lost  their  fear.  The  chimpanzees,  except  one  baby 
which  took  no  notice,  recognised  the  snakes  at  once  and  fled  back- 
wards, uttering  a  peculiar,  soft  warning  cry.  They  then  became 
more  excited  and  began  to  scream,  getting  high  up  on  the  branches 
or  wire  work  of  their  cages,  but  keeping  their  eyes  fixed  on  the 
enemy  all  the  time.  They  soon  took  a  little  courage  and  drew 
nearer  in  a  body,  chattering  loudly,  but  fled  off  screaming  again. 
The  panic  in  the  presence  of  snakes  was  most  sudden  and  complete 
in  the  case  of  orangs.  When  I  tried  the  experiment,  there  were 
two  unusually  fine  examples  in  the  collection,  one  a  large  and 
probably  adult  male,  the  other  a  well-grown  young  female  that  had 
been  two  years  in  the  Gardens  and  was  very  tame  and  gentle. 
Both  of  these  animals  were  usually  most  deliberate  in  their 
movements,  coming  slowly  across  the  cage  even  for  their  favourite 
food,  and  climbing  as  if  it  were  too  much  trouble  to  move.  But 
as  soon  as  they  caught  sight  of  a  snake  and  long  before  it  was 
near  them,  they  fled  silently,  but  with  the  most  unusual  celerity, 
climbing  as  far  out  of  reach  as  possible. 

Most  certainly  it  would  be  cruel  to  supply  snakes  with  living 
monkeys  as  food.  Except  for  a  few  of  the  more  intelligent  passerine 
birds,  monkeys  are  the  only  animals  with  an  instinctive  deep- 
seated  terror  of  snakes.  Such  an  instinctive  terror  does  not  exist 
in  most  animals,  and  certainly  there  is  no  trace  of  it  in  any  of  the 
birds  and  mammals,  the  frogs  and  fishes  that  are  usually  given 
alive  to  snakes.  The  instinctive  dread  of  snakes  that  so  many, 
perhaps  most,  human  beings  display  is  simply  one  of  the  many 
legacies  that  we  have  inherited  from  our  monkey-like  ancestors, 


202  CHILDHOOD  OF  ANIMALS 

and  we  are  quite  wrong  if  we  suppose  that  all  animals  or  most 
animals  possess  it. 

Whilst  I  was  making  these  observations,  I  was  anxiously  on  the 
watch  for  any  signs  of  the  fascination  which  so  many  persons  say 
is  exercised  by  snakes  on  other  animals,  especially  on  birds.  I 
have  now  seen  a  very  large  number  of  birds  and  small  animals  in* 
the  presence  of  snakes,  both  under  natural  conditions  and  in  cap- 
tivity, but  I  have  never  seen  any  trace  of  what  is  described  so  often* 
and  so  graphically,  of  a  bird  or  little  mammal  being  fixed  by  the' 
beady  glittering  eye  of  its  enemy,  and  then  inevitably,  drawn  by 
some  invisible  force,  slipping  down  the  branch  or  along  the  ground 
until  it  falls  into  the  jaws  of  the  reptile.  What  I  have  seen  again 
and  again  is  a  display  of  the  power  of  attention.  A  sudden  move- 
ment may  frighten  away  a  bird  or  mammal  at  once,  but  if  any  object 
— the  tip  of  an  umbrella,  the  human  hand,  or  the  head  of  a  snake — 
be  pushed  forwards  very  slowly  and  quietly,  the  bird  or  mammal 
turns  round,  fixes  its  attention  on  the  moving  spot,  and  if  no  sudden 
noise  or  jerk  be  made,  the  umbrella  or  the  hand  may  reach  the 
creature,  or  the  snake  come  at  striking  distance  of  its  victim.  But 
I  have  never  seen  any  sign  of  the  victim  being,  so  to  say,  magnetised 
or  itself  approaching  the  snake,  and  at  any  moment  too  great 
eagerness  on  the  part  of  the  snake,  or  any  sudden  noise  makes  the 
prey  move  off. 

So  far  as  I  know,  none  of  the  toads,  frogs,  or  newts  helps  to  feed 
the  young.  When  the  tadpoles  get  into  water,  they  have  to  forage* 
for  themselves,  and  they  are  greedy,  omnivorous  creatures,  hunting! 
everywhere  and  not  disdaining  flesh,  fish,  or  vegetable.  They 
have  not  the  strength  to  attack  large  living  creatures,  but  with 
then:  horny  jaws  they  are  able  to  rasp  and  gnaw  decaying  animal 
matter  or  the  tissues  of  plants.  When  the  tadpoles  of  frogs  change 
into  little  frogs,  the  digestive  tract  also  changes.  The  intestinal 
canal  of  the  tadpole  is  very  long  in  proportion  to  the  size  of  the 
creature,  and  is  twisted  up  into  a  spiral,  whilst  the  adult,  which 
is  purely  carnivorous  or  insectivorous,  has  a  much  shorter  and 
straighter  digestive  tube.  Tadpoles  seem  to  find  their  food  much 
more  by  smell  than  by  sight.  If  they  are  accustomed  to  be  fed  on 
shredded  meat,  they  will  pay  no  attention  to  it,  if  it  be  sealed  in 
a  thin  and  transparent  tube  before  being  thrown  into  the  water ; 
but  if  a  drop  of  meat  juice  be  squeezed  into  the  water  in  which  they* 
are  swimming,  the  tadpoles  at  once  become  excited,  and  hunt  in 
every  direction  for  the  appetising  substance.  Frogs  and  toads, 


THE  FOOD  OF  YOUNG  ANIMALS  203 

on  the  other  hand,  select  their  prey  by  sight,  and  they  quickly 
starve  if  from  any  accident  they  become  blind. 

A  set  of  very  famous  experiments  was  made  many  years  ago  on 
the  feeding  of  the  tadpoles  of  the  common  frog.  Young  tadpoles 
were  believed  not  to  have  quite  decided  as  to  whether  they  were 
going  to  become  males  or  females,  and  their  anatomy  shows  that 
they  retain  at  least  a  good  many  of  the  structures  of  both  sexes 
until  they  are  nearly  ready  to  go  through  the  metamorphosis, 
during  which  the  organs  of  one  sex  develop  and  those  of  the  other 
degenerate.  In  an  ordinary  set  of  young  tadpoles  nearly  ready 
to  become  frogs,  the  sexes  are  fairly  evenly  balanced,  but  there  is 
a  slight  excess  of  females.  E.  Yung,  a  distinguished  French 
naturalist,  fed  one  set  of  very  young  tadpoles  entirely  on  beef  until 
they  were  nearly  mature,  a  second  set  on  fish  and  a  third  set  on 
the  flesh  of  frogs.  He  found  that  in  the  first  set  the  percentage 
of  females  rose  to  78,  in  the  second  to  81  and  in  the  third  to  92. 
It  seemed,  in  fact,  as  if  the  food  most  like  the  body  of  the  adult, 
and  therefore  most  nutritious  for  the  animal,  favoured  the  produc- 
tion of  females,  whilst  a  poorer  fare  led  to  the  production  of  males. 
Other  observers  have  repeated  the  experiments,  but  with  conflicting 
results.  I,  myself,  reared  tadpoles  for  several  successive  summers, 
feeding  one  set  of  a  hundred  on  vegetable  matter  with  very  little 
animal  food,  and  another  set  entirely  on  animal  food,  and  examining 
the  sexes  afterwards.  I  got  results  that  differed  widely  from  year 
to  year.  The  chief  trouble  is  that  however  carefully  the  tadpoles 
be  kept,  with  plenty  of  running  water  and  with  the  removal  of  all 
fragments  of  food  soon  after  each  meal,  the  mortality  is  very  high, 
and  it  is  a  fortunate  result  to  rear  twenty  or  thirty  out  of  the  hundred. 
Similar  attempts  have  been  made  to  decide  the  sex  of  higher  animals, 
even  of  human  beings,  by  the  kind  of  food  given  to  the  mother 
before  the  young  are  born,  but  there  has  been  no  success,  and  most 
naturalists  now  believe  that,  at  least  in  the  vertebrate  animals,  the 
sex  is  not  determined  by  external  conditions  such  as  the  nature  of 
the  food. 


CHAPTER  XIII 
THE  TAMING  OF  YOUNG  ANIMALS 

PRIMITIVE  man  was  a  hunter  almost  before  he  had  the  intelligence 
to  use  weapons,  and  from  the  earliest  times  he  must  have  learned 
something  about  the  habits  of  the  wild  animals  he  pursued  for  food 
or  for  pleasure,  or  from  which  he  had  to  escape.  It  was  probably 
as  a  hunter  that  he  first  came  to  adopt  young  animals  which  he 
found  in  the  woods  or  the  plains,  and  made  the  surprising  discovery 
that  these  were  willing  to  remain  under  his  protection  and  were 
pleasing  and  useful.  He  passed  gradually  from  being  a  hunter 
to  becoming  a  keeper  of  flocks  and  herds.  From  these  early  days 
to  the  present  time,  the  human  race  has  taken  an  interest  in  the 
lower  animals,  and  yet  extremely  few  have  been  really  domesticated. 
The  living  world  would  seem  to  offer  an  almost  unlimited  range  of 
creatures  which  might  be  turned  to  our  profit,  and  as  domesticated 
animals  minister  to  our  comfort  or  convenience.  And  yet  it  seems 
as  if  there  were  some  obstacle  rooted  in  the  nature  of  animals  or 
in  the  powers  of  man,  for  the  date  of  the  adoption  by  man  of  the 
few  domesticated  species  lies  in  remote,  prehistoric  antiquity.  The 
surface  of  the  earth  has  been  explored,  the  physiology  of  breeding 
and  feeding  has  been  studied,  our  knowledge  of  the  animal  kingdom 
has  been  vastly  increased,  and  yet  there  is  hardly  a  beast  bred  in 
the  farmyard  to-day  with  which  the  men  who  made  stone  weapons 
were  not  acquainted  and  which  they  had  not  tamed.  Most  of  the 
domestic  animals  of  Europe,  America  and  Asia  came  originally 
from  Central  Asia,  and  have  spread  thence  in  charge  of  their  masters, 
the  primitive  hunters  who  captured  them. 

No  monkeys  have  been  domesticated.  Of  the  carnivores  only 
the  cat  and  the  dog  are  truly  domesticated.  Of  the  ungulates 
there  are  horses  and  asses,  pigs,  cattle,  sheep,  goats  and  reindeer. 
Among  rodents  there  are  rabbits  and  guinea-pigs,  and  possibly 
some  of  the  fancy  breeds  of  rats  and  mice  should  be  included. 
Among  birds  there  are  pigeons,  fowls,  peacocks  and  guinea- 
fowl,  and  aquatic  birds  such  as  swans,  geese  and  ducks,  whilst  the, 

204 


THE  TAMING  OF  YOUNG  ANIMALS          205 

only  really  domesticated  passerine  bird  is  the  canary.  Goldfish 
are  domesticated,  and  the  invertebrate  bees  and  silk-moths  must  not 
be  forgotten.  It  is  not  very  easy  to  draw  a  line  between  domesticated 
animals  and  animals  that  are  often  bred  in  partial  or  complete 
captivity.  Such  antelopes  as  elands,  fallow-deer,  roe-deer,  and 
the  ostriches  of  ostrich  farms  are  on  the  border-line  of  being 
domesticated. 

It  is  also  difficult  to  be  quite  certain  as  to  what  is  meant  by  a 
tame  animal.  Cockroaches  usually  scuttle  away  when  they  are 
disturbed  and  seem  to  have  learnt  that  human  beings  have  a  just 
grievance  against  them.  But  many  people  have  no  horror  of  them. 
A  pretty  girl,  clean  and  dainty  in  her  ways,  and  devoted  to  all 
kinds  of  animals,  used  to  like  sitting  in  a  kitchen  that  was  infested 
with  these  repulsive  creatures,  and  told  me  that  when  she  was 
alone,  they  would  run  over  her  dress  and  were  not  in  the  least 
startled  when  she  took  them  up.  I  have  heard  of  a  butterfly 
which  used  to  come  and  sip  sugar  from  the  hand  of  a  lady,  and 
those  who  have  kept  spiders  and  ants  declare  that  these  intelligent 
creatures  learn  to  distinguish  their  friends.  So  also  fish  like  the 
great  carp  in  the  garden  of  the  palace  of  Fontainebleau,  and  many 
fishes  in  aquaria  and  private  ponds  learn  to  come  to  be  fed.  I 
do  not  think,  however,  that  these  ought  to  be  called  tame  animals. 
Most  of  the  wild  animals  in  menageries  very  quickly  learn  to  distin- 
guish one  person  from  another,  to  obey  the  call  of  their  keeper 
and  to  come  to  be  fed,  although  certainly  they  would  be  dangerous 
even  to  the  keeper  if  he  were  to  enter  their  cages.  To  my  mind, 
tameness  is  something  more  than  merely  coming  to  be  fed,  and 
in  fact  many  tame  animals  are  least  tame  when  they  are  feeding. 
Young  carnivores,  for  instance,  which  can  be  handled  freely  and 
are  affectionate,  very  seldom  can  be  touched  whilst  they  are  feed- 
ing. The  real  quality  of  tameness  is  that  the  tame  animal  is  not 
merely  tolerant  of  the  presence  of  man,  not  merely  has  learned  to 
associate  him  with  food,  but  takes  some  kind  of  pleasure  in  human 
company  and  shows  some  kind  of  affection. 

On  the  other  hand  we  must  not  take  our  idea  of  tameness  merely 
from  the  domesticated  animals.  These  have  been  bred  for  many 
generations,  and  those  that  were  most  wild,  and  that  showed  any 
resistance  to  man,  were  killed  or  allowed  to  escape.  Dogs  are 
always  taken  as  the  supreme  example  of  tameness,  and  sentimen- 
talists have  almost  exhausted  the  resources  of  language  in  praising 
them.  Like  most  people,  I  am  very  fond  of  dogs,  but  it  is  an 


206  CHILDHOOD  OF  ANIMALS 

affection  without  respect.  Dogs  breed  freely  in  captivity,  and 
in  the  enormous  period  of  time  that  has  elapsed  since  the  first 
hunters  adopted  wild  puppies,  there  has  been  a  constant  selection 
by  man,  and  every  dog  that  showed  any  independence  of  spirit 
has  been  killed  off.  Man  has  tried  to  produce  a  purely  subservient 
creature,  and  has  succeeded  in  his  task.  No  doubt  a  dog  is  faithful 
and  affectionate,  but  he  would  be  shot  or  drowned,  or  ordered  to 
be  destroyed  by  the  local  magistrate  if  he  were  otherwise.  A  small 
vestige  of  the  original  spirit  has  been  left  in  him,  merely  from  the 
ambition  of  his  owners  to  possess  an  animal  that  will  not  bite 
them,  but  will  bite  any  one  else.  And  even  this  watch-dog  trait 
is  mechanical,  for  the  guardian  of  the  house  will  worry  the  harmless, 
necessary  postman,  and  welcome  the  bold  burglar  with  fawning 
delight.  The  dog  is  a  slave,  and  the  crowning  evidence  of  his 
docility,  that  he  will  fawn  on  the  person  who  has  beaten  him,  is 
the  result  of  his  character  having  been  bred  out  of  him.  The  dog 
is  an  engaging  companion,  an  animated  toy  more  diverting  than 
the  cleverest  piece  of  clockwork,  but  it  is  only  our  colossal  vanity 
that  makes  us  take  credit  for  the  affection  and  faithfulness  of  our 
own  particular  animal.  The  poor  beast  cannot  help  it ;  all  else 
has  been  bred  out  of  him  generations  ago. 

When  wild  animals  become  tame,  they  are  really  extending  or 
transferring  to  human  beings  the  confidence  and  affection  they 
naturally  give  their  mothers,  and  this  view  will  be  found  to  explain 
more  facts  about  tameness  than  any  other.  Every  creature  that 
would  naturally  enjoy  maternal  (or,  it  would  be  better  to  say, 
parental  care,  as  the  father  sometimes  shares  in  or  takes  upon  him- 
self the  duty  of  guarding  the  young)  is  ready  to  transfer  its  devotion 
to  other  animals  or  to  human  beings,  if  the  way  be  made  easy  for 
it,  and  if  it  be  treated  without  too  great  violation  of  its  natural 
instincts.  The  capacity  to  be  tamed  is  greatest  in  those  animals 
that  remain  longest  with  their  parents  and  that  are  most  intimately 
associated  with  them.  The  capacity  to  learn  new  habits  is  greatest 
in  those  animals  which  naturally  learn  most  from  their  parents, 
and  in  which  the  period  of  youth  is  not  merely  a  period  of  growing, 
a  period  of  the  awakening  of  instincts,  but  a  time  in  which  a 
real  education  takes  place.  These  capacities  of  being  tamed  and 
of  learning  new  habits  are  greater  in  the  higher  mammals  than  in 
the  lower  mammals,  in  mammals  than  in  birds,  and  in  birds  than 
in  reptiles.  They  are  very  much  greater  in  very  young  animals, 
where  dependence  on  the  parents  is  greatest,  than  in  older  animals, 


THE  TAMING  OF  YOUNG  ANIMALS         207 

'and  they  gradually  fade  away  as  the  animal  grows  up,  and  are 
least  of  all  in  fully  grown  and  independent  creatures  of  high  intelli- 
gence. These,  because  they  are  intelligent,  may  learn,  even  when 
they  have  been  captured  as  adults,  that  they  have  nothing  to  fear, 
that  the  bars  of  their  cage  or  the  boundaries  of  their  enclosure 
not  only  restrain  them  from  attacking  persons  outside,  but  restrain 
the  persons  outside  from  disturbing  them.  Very  fierce  and  fully 
adult  mammals  will  settle  down  quietly  to  captivity,  will  learn 
that  the  visit  of  a  keeper  is  a  pleasant  source  of  food,  that  cleaning 
out  the  litter  and  washing  the  cage  are  not  schemes  to  annoy  them, 
and  almost  in  proportion  to  their  intelligence  will  tolerate  captivity. 
The  shyest  of  wild  birds  will  breed  peacefully  a  few  inches  from 
the  wire  work  of  their  enclosure,  or  will  display  complete  fearless- 
mess  of  the  visitors  who  are  on  the  other  side  of  the  fence,  often 
isimply  because  birds  that  are  naturally  intelligent  have  learned  to 
ibe  shy  in  the  wild  condition,  and  equally  learn  not  to  be  shy  where 
they  are  protected.  Wood-pigeons  in  the  open  fields  are  amongst 
the  shyest  and  wariest  of  the  native  creatures  of  Great  Britain, 
but  they  have  learned  almost  complete  fearlessness  in  the  London 
parks.  But  these  are  not  tame  ;  they  have  no  pleasure  in  the  society 
of  man  or  real  confidence  in  him.  These  qualities  can  be  acquired 
only  when  the  young  creatures  are  taken  over  by  man  whilst  they 
are  still  young  and  when  it  is  still  their  natural  habit  to  be  cherished 
and  protected.  Later  on  in  this  chapter  I  shall  say  something 
about  the  duration  of  tameness  as  young  animals  grow  up.  It 
is  clear;  however,  that  we  must  be  prepared  to  find  that  it  may 
not  last.  Just  as  it  is  the  natural  instinct  of  parents  to  cherish 
their  young,  so  also  a  time  comes,  except  in  gregarious  animals, 
when  this  instinct  is  reversed,  and  when  the  parents  drive  away 
their  young,  and  when  the  young  themselves  have  to  face  the  perils 
iof  life  with  a  wary  suspicion  and  a  fierceness  that  are  extremely 
different  from  their  former  habits.  And  even  in  gregarious  animals, 
a  time  comes  when  the  savage  battle  of  sex  begins,  and  when 
creatures  that  at  all  other  times  retain  the  friendly  and  gentle 
habits  of  youth  are  dangerous  to  approach. 

All  young  primates  are  gentle  and  easy  to  tame.  The  gorilla 
is  reported  to  be  one  of  the  most  savage,  as  he  is  one  of  the  most 
powerful  and  well  armed,  of  creatures.  I  do  not  think  that  any 
adult  gorilla  has  ever  been  captured  alive.  But  young  gorillas 
are  very  well  known,  and  many  individuals  have  been  brought  to 
Europe  at  ages  varying  from  a  few  months  to  five  or  six  years.  I, 


208  CHILDHOOD  OF  ANIMALS 

myself,  have  seen  five,  of  different  ages.  They  were  all  extremely 
gentle  and  affectionate,  ready  to  make  friends  at  once,  and  amazingly 
intelligent.  Unfortunately  they  are  very  delicate,  and  seldom 
live  more  than  a  few  weeks  in  this  country.  Although  no  animals 
are  more  attractive  and  none  is  more  to  be  desired  in  a  Zoo- 
logical Collection,  I  have  refused,  as  Secretary  of  the  Zoological 
Society  of  London,  to  encourage  their  importation  by  dealers, 
and  now  decline  to  purchase  them.  If  some  one  who  was  really 
fond  of  animals  and  intelligent  in  managing  them  were  to  obtain 
specimens  in  West  Africa,  and  were  to  keep  them  there  until 
they  had  become  thoroughly  accustomed  to  human  society  and 
to  the  food  that  they  would  afterwards  receive,  I  see  no  reason 
why  they  should  not  be  successfully  reared,  and  I  have  no  doubt 
but  that  they  would  be  found  to  surpass  the  other  great  apes  in 
the  humanity  of  their  intelligence  as  they  do  in  size  and  structure. 
Orangs  are  better  known  because,  although  they,  too,  are  delicate, 
they  have  been  reared  much  more  successfully  in  captivity.  The 
adults  in  their  native  woods,  the  steaming  tropical  forests  of  the 
Malay  Archipelago,  are  almost  as  suspicious  of  man  as  the  gorilla, 
and  their  enormous  jaws  and  powerful  hands  and  feet  make  them 
dangerous  foes.  Young  orangs  are  extraordinarily  docile  and 
very  affectionate,  and  have  been  taught  many  strange  tricks — to 
wear  clothes,  to  sit  at  table  for  their  food  and  to  eat  and  drink 
with  spoons  and  cups.  They  are  slow  and  sedate  in  their  move- 
ments, and  as  they  are  watchful  and  attentive,  they  quickly  learn 
what  their  keepers  wish  them  to  do.  But  although  they  are  more 
hardy  than  gorillas,  they  have  to  be  kept  under  such  careful  condi- 
tions and  have  lives  so  uncertain  that  their  training  has  never 
reached  very  great  lengths. 

Chimpanzees  are  much  the  most  hardy  of  the  anthropoid  apes, 
and  their  character  and  capacities  are  best  known.  They  are  all 
extremely  excitable,  and  occasionally  fall  into  almost  hysterical 
fits  of  temper,  when  they  scream  loudly,  and  will  bite  even  their 
best  friends,  and  as  they  have  considerable  strength  and  fight  with 
their  teeth  and  hands  and  feet  simultaneously,  they  are  not  always 
quite  safe.  Because  of  this  disposition,  I  dislike  the  use  of  chim- 
panzees for  performances  at  music-halls  ;  I  am  afraid  that  not 
infrequently  they  have  to  be  beaten  to  bring  them  up  to  the 
prompter's  bell,  and  I  have  noticed  that  the  teeth  of  some  of  the 
most  advertised  performing  chimpanzees  had  been  extracted  or 
broken  off.  Apart  from  occasional  fits  of  temper,  and  if  they 


THE  TAMING  OF  YOUNG  ANIMALS          209 

are  well  treated  and  not  unduly  forced  to  do  tricks  when  they  are 
unwilling,  chimpanzees  show  extreme  affection  and  docility.  They 
recognise  their  friends  after  long  absences  and  show  the  greatest 
excitement  and  joy  when  they  return.  It  is  unnecessary  to  describe 
all  that  they  have  been  taught  to  do  ;  they  ride  cycles,  perform 
on  the  trapeze,  put  on  and  off  clothes,  open  or  close  doors,  help  in 
sweeping  their  cages,  use  forks  and  spoons,  cups  and  drinking-glasses. 
In  the  famous  case  of  Sally,  the  late  Professor  Romanes,  with  the 
patient  help  of  Mansbridge,  the  keeper,  taught  that  chimpanzee 
a  trick  with  straws  which  quite  possibly  implied  the  power  of 
counting  up  to  five.  Mansbridge  has  recently  taught  two  young 
chimpanzees  in  the  London  Zoological  Gardens  a  very  interesting 
performance  which  they  carry  out  at  the  command  of  his  voice, 
with  little  help  from  gestures.  When  he  brings  visitors  to  the 
room,  he  unlocks  the  door  from  the  outside  and  calls  them  to  come 
and  open  it.  He  then  bids  them  salute,  and  they  at  once  climb 
on  a  shelf  and,  sitting  alongside,  place  their  right  hands  to  their 
foreheads.  Next  a  cup  of  milk  and  a  spoon  are  given  to  one  of  them 
and  he  is  told  to  feed  his  sister.  He  proceeds  to  feed  her  with  the 
spoon,  until  he  is  told  that  he  may  now  take  some  himself.  After 
a  varying  number  of  spoonfuls,  Mansbridge  says,  "  Now  put 
down  the  spoon  and  drink  it  out  of  the  cup,"  which  the  animal 
at  once  does.  The  older  monkey  is  then  given  two  pieces  of  apple 
or  banana,  one  large  and  one  small,  and  told  to  give  one  to  his 
sister  ;  he  has  learned  to  select  and  give  her  the  larger  piece.  If 
there  is  a  lady  and  a  man  amongst  the  visitors  he  is  told  to  offer 
a  piece  to  them,  and  invariably  carries  out  what  he  has  been  taught 
by  giving  the  larger  bit  to  the  lady  and  the  smaller  to  the  man, 
certainly  distinguishing  between  the  pieces  and  the  visitors  without 
any  direction  from  the  keeper. 

Gibbons  are  less  intelligent,  but  young  gibbons  soon  become  docile 
and  are  always  gentle  and  friendly.  One  of  those  now  at  the  London 
Zoological  Gardens  has  been  taught  to  swing  round  and  round 
a  bar  holding  on  by  his  hands,  and  to  stop  and  reverse  at  the  word 
of  command.  All  young  baboons  and  African,  Asiatic  and  Ameri- 
can monkeys  that  I  have  seen  are  quite  ready  to  become  gentle 
and  tame  and  to  take  to  human  beings,  and  the  various  ingenious 
tricks  that  they  have  been  taught  are  well  known.  Lemurs  are 
less  intelligent,  but  are  equally  ready  to  become  tame. 

Performing  chimpanzees  seldom  live  for  more  than  a  few  years, 
and  I  have  never  seen  one  that  was  nearly  adult.  At  the  Zoological 

C.A.  O 


210  CHILDHOOD  OF  ANIMALS 

Gardens,  the  chimpanzees  as  they  grow  up  seem  to  me  to  become 
less  tame,  but  that  may  be  partly  because  the  keepers  have  to  cease 
being  so  familiar  with  them  when  they  grow  stronger,  and  when 
considerable  force  would  have  to  be  used  if  they  fell  into  a  fit  of 
temper.  The  oldest  chimpanzee  in  the  London  collection  is  cer- 
tainly fully  adult,  as  he  is  at  least  fifteen  years  old,  and  has  remained 
reasonably  docile  with  his  keeper,  but  is  not  quite  safe  with 
others.  For  the  same  reason  baboons  and  monkeys  and  lemurs 
are  not  handled  so  freely  as  they  grow  up,  but  it  certainly  is  my 
opinion  that  apart  from  this,  their  tameness  wears  off. 

All  young  monkeys  are  climbing  animals,  accustomed  first  to 
cling  to  their  parents  and  then  to  run  along  branches  with  the  help 
of  their  hands  and  feet.  They  dislike  being  caught  hold  of,  and, 
until  they  are  really  familiar  with  you,  they  will  be  frightened  or 
try  to  bite  if  you  make  any  attempt  to  seize  them.  If,  however, 
they  are  allowed,  they  will  climb  on  to  you,  running  up  your  arm 
and  sitting  on  your  shoulder,  or  clinging  round  your  neck.  This 
applies  not  only  to  quite  young  monkeys  but  to  many  that  are 
full  grown  ;  they  will  struggle  and  bite  if  you  try  to  grasp  them, 
but  they  will  readily  allow  themselves  to  be  carried.  When  they 
have  become  familiar,  and  are  given  an  arm  by  which  to  hold 
on,  they  will  allow  themselves  to  be  groomed,  to  have  their  fur 
combed  and  brushed,  and  their  faces,  feet  and  hands  and  the 
naked  parts  of  their  body  washed.  One  of  the  difficulties  in  keeping 
monkeys  is  that  it  is  almost  impossible  to  train  them  to  cleanly 
habits.  Like  most  arboreal  animals,  they  have  no  special  place 
to  keep  clean  and  no  natural  disposition  to  avoid  fouling  their 
blanket  or  the  floor  on  which  they  are.  I  have  seen  a  chimpanzee 
that  was  trained  to  use  a  lavatory,  but  it  plainly  acted  as  if  it  were 
one  of  the  tricks  that  it  had  been  taught  to  perform  and  did  not 
associate  it  with  the  object  in  view.  It  would  go  through  the 
operations  when  it  had  no  need,  and  immediately  afterwards  would 
foul  the  floor  or  its  clothes.  With  regard  to  cleanliness,  the  most 
careful  training  can  only  develop  the  natural  instincts  of  animals. 

I  do  not  know  any  exception  to  the  rule  that  carnivores,  which 
are  naturally  accustomed  to  maternal  care,  are  easily  tamed  and 
when  young  make  gentle  and  affectionate  pets.  Baby  tigers;  lions, 
leopards,  cheetahs,  caracals,  lynxes,  all  the  bears,  hyenas,  dogs, 
wolves,  foxes,  and  all  the  smaller  creatures  in  the  group  attach 
themselves  extremely  readily  to  man.  As  they  are  usually  carried 
in  the  mouth  by  the  mother,  unlike  monkeys,  they  expect  to  be 


THE  TAMING  OF  YOUNG  ANIMALS          211 

picked  up,  and  prefer  firm,  almost  rough,  handling.  As  the  mother 
licks  them  over  and  cleans  them,  they  like  being  brushed  and 
scrubbed  with  a  rough  damp  towel.  Most  of  all  they  like  being 
caressed  and  petted  and  allowed  to  sleep  snuggling  in  a  warm  lap. 
Not  food,  but  warmth  and  physical  contact  are  the  surest  ways 
to  their  affections.  But  all  of  them,  and  especially  the  cats,  retain 
a  good  deal  of  independence.  They  like  to  be  left  alone  sometimes, 
to  retire  into  a  particular  dark  corner  which  they  have  selected, 
and  will  be  rather  unpleasant  if  they  are  dragged  out  when  they 
do  not  wish  society.  If  they  are  left  alone,  they  will  soon  come 
back.  To  be  fond  of  companionship  is  no  peculiar  gift  of  the  dog. 
All  the  carnivores  dislike  being  left  alone  long,  and  will  scream 
loudly  if  they  are  shut  up,  or  quickly  learn  the  habits  of  their  owners 
and  follow  them  from  place  to  place. 

It  is  no  part  of  the  domesticated  nature  of  the  cat  and  dog  that 
these  are  easy  to  train  to  cleanliness  in  a  house.  In  their  very 
young  days,  the  cubs  and  kittens  of  the  catlike  carnivores  and  of 
the  wolves  and  dogs  and  foxes  are  kept  clean  by  the  mothers,  but 
as  soon  as  they  are  able  to  move  about  they  are  scrupulous  in 
avoiding  the  soiling  of  their  bedding,  or  the  floor  of  the  room  in 
which  they  are  kept,  and  if  a  box  with  sand,  or  better  still  with 
fresh  turf,  is  kept  in  a  dark  corner,  they  will  find  it  themselves  and 
hardly  have  to  be  taught.  It  is  almost  a  certain  sign  of  illness  in 
any  of  these  creatures  if  they  become  dirty  in  their  habits.  The 
various  small  carnivores  that  live  in  trees,  like  palm-civets  and  so 
forth,  are  a  little  more  troublesome,  but  they  are  very  easily  taught. 
When  the  teeth  begin  to  develop,  young  carnivores  naturally  try 
them  on  every  possible  object,  living  or  inanimate,  within  their 
reach,  and  it  is  necessary  to  teach  them  not  to  bite  their  owners, 
as  even  in  play  they  may  do  a  good  deal  of  damage.  They  even 
bite  their  mother,  until  she  teaches  them,  with  rather  sharp  pats 
from  her  paw,  what  it  is  permitted  to  bite  and  what  is  taboo.  With 
the  different  kinds  of  cats,  from  tigers  to  the  domestic  cat,  a  little 
rap  on  the  upper  surface  of  the  nose  is  the  safest  and  most  effectual 
form  of  punishment.  When  this  has  been  done  once  or  twice,  it 
is  quite  enough  to  lay  the  finger  on  the  nose,  and  the  little  animal 
will  understand  and  remember.  It  is  more  difficult  to  teach  them 
not  to  use  their  claws  when  they  get  excited  in  play,  or  merely 
when  they  are  jumping  or  climbing  on  one.  The  claws  of  small 
leopards,  caracals  and  so  forth  are  as  sharp  as  needles,  and  when 
they  are  quite  young  they  dig  them  in  automatically.  Later  on 


212  CHILDHOOD  OF  ANIMALS 

when  they  are  older,  they  will  romp  in  the  wildest  way,  strike  quite 
hard  blows  with  the  paws,  and  submit  to  very  rough  handling 
without  unsheathing  their  claws.  It  is  only  when  they  are  being 
teased,  especially  over  food,  or  when  they  are  in  a  temper  and 
are  lying  on  their  backs  refusing  to  be  picked  up,  that  there  is 
any  danger  of  their  striking  with  unsheathed  weapons.  It  is  safer, 
however,  to  keep  the  points  cut ;  this  is  quite  necessary  when  they 
are  babies,  and  if  they  have  been  accustomed  to  the  process  then, 
they  will  allow  it  to  be  done  when  they  are  nearly  grown  up.  Each 
claw  should  be  pressed  out  of  its  sheath  in  turn,  and  the  end  nipped 
off  with  very  sharp  scissors  or  nail-clippers.  The  instrument  must 
be  both  strong  and  sharp,  as  the  nails  split  rather  easily.  The 
instinctive  movements  of  young  carnivores  are  fitted  to  retain 
hold  of  a  living,  struggling  prey,  and  the  most  certain  way  to  be 
bitten  or  clawed  is  to  stretch  out  the  hand  timidly  and  try  to  draw 
it  back.  The  creatures  must  be  seized  firmly  and  at  the  first  move- 
ment, and  if  they  put  out  their  claws  or  close  their  teeth,  do  not 
try  to  pull  the  hand  away.  They  will  do  no  further  damage  and 
after  holding  on  for  a  few  minutes  they  will  let  go.  Those  who 
handle  young  carnivores,  however,  must  expect  to  be  bitten  or 
scratched  sometimes,  either  in  temper  or  in  p'ay,  and  disinfectants 
should  always  be  at  hand  and  be  applied  at  once.  I  do  not  think 
that  the  little  wounds  from  the  teeth  are  often  dangerous,  but 
the  claws  are  always  rather  dirty  and  may  easily  convey  disease 
germs. 

Carnivores  have  excellent  memories  and  recognise  their  friends 
even  after  years  of  absence.  Mr.  Carl  Hagenbeck,  of  Hamburg, 
who  has  probably  handled  and  trained  more  young  lions  than  any 
other  person,  and  as  an  important  part  of  his  business  for  many  years 
has  been  supplying  performing  animals  to  travelling  menageries 
and  circus  troupes,  has  told  me  that  adult  lions  which  he  had  not 
seen  for  many  years  have  welcomed  him  with  every  appearance 
of  pleasure.  He  is  a  man  of  iron  nerve,  with  a  great  love  of  animals 
and  most  unusual  knowledge  of  their  ways,  and  I  have  seen  adult 
lions  that  had  been  bred  and  reared  in  his  establishment,  but  which 
had  not  been  specially  trained,  as  friendly  with  him  as  if  they  had 
been  still  young  cubs.  There  is  no  doubt  that  such  animals  which 
have  been  tamed  and  handled  when  they  are  young  retain  much 
of  their  friendliness  and  docility.  Animals  that  come  to  the  Zoo- 
logical Gardens  as  young  and  tame  cubs  generally  remain  much 
more  easy  to  deal  with,  and  again  and  again,  long  after  they  had 


THE  TAMING  OF  YOUNG  ANIMALS         213 

ceased  to  be  petted  and  handled,  I  have  seen  them  welcome  their 
original  owner.  The  same  difficulty  exists  with  carnivores  which 
have  grown  up  as  with  the  large  apes.  The  danger  of  continuing 
to  treat  them  with  unconcern  is  too  great,  as  the  result  of  a  fit  of 
temper  or  a  sudden  fright  might  very  readily  be  fatal  to  those 
who  had  rashly  ventured  within  their  reach.  It  is  certain,  more- 
over, that  they  distinguish  acutely  between  persons,  and  an  animal 
that  is  quite  tame  with  one  keeper  or  person  may  be  extremely 
dangerous  with  others.  They  are  extremely  nervous,  and  the 
slightest  hesitation  or  want  of  resolution  in  approaching  them 
may  alarm  them  and  cause  trouble.  It  is  not  quite  certain,  there- 
fore, what  would  be  the  result  of  the  experiment  of  continuing  to 
treat  fully  grown  lions,  tigers,  bears  and  so  forth  with  the  same 
familiarity  as  when  they  were  cubs.  With  the  smaller  wild  carni- 
vores, however,  there  is  no  doubt  that  as  they  become  adult  the 
natural  instincts  of  predaceous  creatures  armed  for  destruction 
tend  to  overrule  their  tameness.  They  cease  to  have  complete 
confidence  in  their  owners,  become  wary  and  intensely  suspicious 
and  wholly  unsafe,  at  least  with  strangers.  Even  creatures  so  near 
the  dog  as  wolves,  dingos  and  foxes,  and  most  of  the  small  carni- 
vores, have  to  be  given  up  as  pets  when  they  are  adult.  This  is 
simply  following  the  natural  order  of  events.  In  the  wild  condition, 
apart  from  the  influence  of  man,  they  are  gentle  and  affectionate 
when  they  are  young,  but  when  they  are  fully  grown  have  to  display 
habits  more  suited  for  the  unfriendly  world  in  which  they  live. 
Human  influence  retards  but  does  not  prevent  this  inevitable  and 
necessary  change. 

Although  I  am  inclined  to  admit,  reluctantly,  the  truth  of  the 
general  belief  that  the  friendliness  of  carnivores  is  an  episode  of 
their  youth,  there  are  two  other  well-known  popular  beliefs  about 
them  for  which  I  have  found  no  evidence.  The  first  is  the  supposed 
change  in  their  habits  at  night.  I  have  again  and  again  been  told, 
with  regard  to  young  tame  animals  in  my  own  possession,  that 
they  might  be  safe  by  day,  but  that  at  night  their  prowling, 
savage  instincts  would  awaken,  and  that  they  would  seize  me  by 
the  throat.  I  have  often  gone  at  night  to  play  with  nearly  full- 
grown  young  leopards,  both  the  common  leopards  and  snow 
leopards,  which  knew  me  by  day,  and  I  have  found  them  as 
friendly  and  as  gentle  then  as  at  any  other  time.  A  young  tame 
caracal  slept  nightly  on  a  towel  alongside  my  pillow  until  it  was 
nearly  a  year  old,  and  although  it  was  sometimes  restless  and 


214  CHILDHOOD  OF  ANIMALS 

would  wake  me  up  to  be  let  out  by  patting  my  face,  there  was  no 
change  in  its  behaviour  at  night  or  in  the  day. 

We  have  all  been  familiar  since  we  were  children  with  the  story 
of  the  English  officer  in  India  who  had  brought  up  a  young  tiger 
as  a  pet.  One  evening,  when  the  tiger,  now  nearly  full  grown, 
was  lying  by  the  side  of  his  master,  who  was  taking  his  ease  in  his 
arm-chair,  the  faithful  servant  saw  with  horror  that  there  was 
a  little  trickle  of  blood  from  the  hand  of  his  master,  and  that  the 
tiger  was  eagerly  licking  it.  Knowing  that  the  first  taste  of  blood 
would  arouse  all  the  savage  instincts  of  the  animal,  and  that  presently 
his  master  would  be  devoured,  the  servant  rushed  for  a  rifle,  and, 
creeping  up  cautiously  to  the  tiger,  shot  it  through  the  heart.  We 
have  all  read  the  story,  and  most  of  us  have  been  told  it  many  times 
by  retired  Anglo-Indians  to  whose  intimate  friends  it  had  occurred, 
but  whose  lives  were  fortunately  spared  to  bear  witness  to  other 
familiar  stories  of  the  East.  Young  carnivores  in  this  country  are 
not  in  the  least  excited  by  human  blood.  Long  before  they  are 
full  grown  they  have  become  accustomed  to  the  taste  of  fresh 
blood,  for  there  is  no  better  occasional  food  for  them  than  a  freshly 
killed  sparrow,  pigeon  or  young  rabbit,  according  to  their  size. 
When  my  own  hand  has  been  bleeding  from  an  unlucky  scratch 
(and  it  may  bleed  a  good  deal)  I  have  offered  it  again  and  again 
to  my  young  carnivorous  friends,  and  they  are  not  in  the  least 
excited.  They  much  prefer  milk. 

Young  seals,  sea-lions  and  walruses  are  extremely  easy  to  tame. 
It  is  quite  certain  that  they  remain  with  their  mothers  for  a  long 
time  and  are  very  fond  of  companionship.  As  those  that  arrive 
at  the  Zoological  Gardens  are  generally  young  animals  which  have 
recently  been  taken  from  their  mothers,  at  first  they  mope  very 
much,  and  it  is  extremely  difficult  to  induce  them  to'  eat  or  to  be 
consoled.  It  is  curious  that  the  seals  which  have  most  experience 
of  man,  such  as  the  grey  seal  and  the  common  seal,  seem  to  have 
almost  an  inherited  fear  of  him,  and  although  they  can  be  tarned, 
do  not  settle  down  so  quickly,  and  not  infrequently  pine  and  die. 
Seals  from  remoter  waters,  such  as  the  elephant  seal  from  the 
South  Indian  Ocean,  the  sea-lions  from  Africa,  Patagonia  and 
California,  and  the  walruses  from  the  icy  seas  of  the  North  become 
reconciled  to  captivity  almost  at  once.  A  similar  difference  between 
the  wild  animals  of  civilised  and  populous  countries  and  those  of 
remoter  regions  exists  in  many  other  cases.  Fear  of  man  is  no 
special  instinct  of  animals ;  those  that  have  little  acquaintance 


THE  TAMING  OF  YOUNG  ANIMALS          215 

with  him  are  curious  about  him  rather  than  frightened  of  him, 
but  those  that  have  been  forced  to  make  his  acquaintance  at  close 
quarters  have  had  to  learn  to  avoid  him  and  fear  him  almost  as  a 
condition  of  their  existence.  When  seals  of  any  kind  do  survive 
the  early  days  of  their  captivity,  they  become  very  tame  and  docile, 
following  their  keepers  from  place  to  place  and  being  anxious  to 
rub  against  them  and  nuzzle  them.  It  must  be  even  more  difficult 
for  these  animals  than  it  is  for  the  predaceous  land  carnivores  to 
learn  the  serious  business  of  hunting,  and  it  is  probably  only  after 
a  long  apprenticeship  with  their  mothers  that  they  become  able 
to  find  and  to  catch  fish  for  themselves.  It  is  not  surprising  there- 
fore that  they  are  friendly  and  attentive  and  have  high  powers  of 
intelligence.  Common  seals,  grey  seals  and  sea-lions  have  frequently 
lived  in  zoological  gardens  long  after  they  have  become  adult,  and 
I  have  never  heard  of  a  case  in  which  they  lost  their  tameness  or 
were  in  any  way  dangerous  to  their  keepers.  They  are  all  gre- 
garious, living  in  numbers  in  their  favourite  haunts,  and  certainly 
giving  one  another  warning  of  approaching  danger,  and  it  is  only 
in  the  breeding  season  that  the  males  are  savage,  when  they 
engage  in  fierce  battles  and  try  to  steal  each  other's  wives. 

The  young  of  hoofed  animals  are  all  accustomed  to  run  with  their 
mother  from  their  first  days,  and  most  of  them  readily  transfer 
their  companionship  to  man.  Few  of  them  show  any  high  degree 
of  intelligence,  but  they  distinguish  between  individuals,  recognis- 
ing them  both  by  voice  and  by  smell,  but  to  a  much  smaller  extent 
by  sight.  They  like  being  stroked  and  fondled,  but,  except  when 
they  are  very  young,  resent  being  seized  hold  of  or  lifted,  and  are 
extremely  easily  scared  by  any  unusual  sight  or  sound.  Not  only 
do  they  follow  their  mothers  when  they  are  young,  but  most  of  them 
are  gregarious,  and  the  herds  or  flocks  are  accustomed  to  follow 
a  leader.  This  is  true  even  in  the  domesticated  animals,  and  the 
familiar  English  sight  of  a  herdsman  or  shepherd  driving  his 
animals  with  barking  dogs  and  much  shouting,  or  struggling  with 
a  pig,  is  wholly  unnatural.  Ungulate  animals,  young  or  old,  learn 
to  follow  a  human  being  as  surely  as  they  would  naturally  follow 
their  mother  or  the  leader  of  their  herd.  Their  affection,  however, 
is  seldom  much  more  than  a  fear  of  being  left  alone,  a  desire  for 
companionship,  and  the  hope  of  getting  some  tit-bit  to  eat.  Those 
that  are  not  domesticated  seldom  retain  much  regard  for  or  con- 
fidence in  human  beings  after  they  have  grown  up,  and  nearly  all 
of  them  are  dangerous  in  the  breeding  season. 


2i6  CHILDHOOD  OF  ANIMALS 

Even  if  they  were  suitable  otherwise  as  pets,  young  tame  ungulates 
must  be  kept  out  of  doors,  for  none  of  them,  or  almost  none  of  them, 
has  the  natural  habit  of  cleanliness,  and  so  they  cannot  be  trained  to 
observe  the  proprieties.  The  best-known  exceptions  are  the  swine, 
which  will  not  foul  their  own  litter  if  they  have  an  opportunity  of 
choice,  and  will  generally  select  a  remote  corner  of  their  run  to 
deposit  their  droppings.  One  other  exception  was  a  great  surprise 
to  me.  My  tame  tree-hyrax,  almost  as  soon  as  it  came  into  my 
possession,  chose  the  old  green  baize  cover  of  a  typewriter,  which 
happened  to  have  been  thrown  down  in  a  corner  of  my  study,  and 
afterwards  remained  faithful  to  this  selection.  When  it  was  kept 
ready  for  it,  it  would  seek  it  out  of  its  own  accord,  and  when  the 
little  animal  was  taken  there  at  night,  before  going  to  bed,  it  at  once 
made  use  of  it.  The  coney,  another  species  of  hyrax,  is,  accord- 
ing to  the  Bible,  "  exceeding  wise/'  but  this  particular  form  of 
wisdom  was  very  unexpected,  and  very  unlike  the  habits  of  other 
hoofed  animals. 

Every  one  knows  that  young  elephants  are  gentle,  playful  and 
friendly,  and  that  they  attach  themselves  strongly  to  their  keepers. 
Their  memory  is  very  good,  and  neither  young  nor  old  elephants 
forget  an  injury  or  a  kindness  easily.  Their  powers  of  climbing, 
balancing  and  jumping,  often  seen  in  trained  performing  elephants, 
are  quite  natural  developments  of  their  capacities,  for  elephants 
are  extremely  active  in  their  native  haunts  and  climb  steep  rocks 
very  well.  They  usually  retain  their  tameness  when  they  grow 
up,  except  at  special  seasons  when  males  are  dangerous.  Their 
docility  is  the  result  of  their  natural  disposition,  their  long  associa- 
tion with  their  mother  and  their  social  habits.  It  is  not  due  to 
domestication.  Even  the  Indian  elephant  is  a  tamed  rather  than 
a  domesticated  animal.  The  stock  is  kept  up  much  more  by  the 
capture  of  wild  animals  than  by  breeding  in  captivity,  and  young 
and  old  African  elephants,  which  have  not  been  domesticated  in 
the  sense  that  has  happened  in  Asia,  are  just  as  docile  and  easy  to 
manage. 

I  have  already  spoken  repeatedly  of  the  hyrax.  It  is  in  every 
sense  a  wild  animal,  and  although  it  has  bred  in  captivity,  I  do 
not  know  of  this  having  gone  on  for  more  than  one  generation.  Nor 
do  I  know  any  one,  except  myself,  who  has  had  the  good  fortune 
to  own  a  tame  tree-hyrax,  but  tame  examples  of  the  animal  from 
South  Africa,  East  Africa  and  Syria  have  been  known,  and  their 
owners  agree  as  to  their  engaging  character.  They  are  amusing, 


THE  TAMING  OF  YOUNG  ANIMALS         217 

very  affectionate,  and  intelligent.  They  are  expert  and  tireless 
climbers,  and  no  doubt  as  a  result  of  their  habit  of  riding  on  the 
back  of  the  mother,  although  they  rather  dislike  being  picked  up, 
they  like  sitting  on  the  ankle  or  hand  or  shoulder.  My  pet  rushes 
to  meet  me  as  soon  as  I  open  the  door  of  the  room  in  which  it  has 
been  kept,  after  an  absence.  It  roams  all  over  my  study,  climbing 
up  the  bookshelves  wherever  there  is  a  vestige  of  foothold ;  I  have 
seen  it  climb  on  the  back  of  a  chair  placed  against  the  smooth, 
polished  front  of  a  chest  of  drawers,  stand  on  tiptoe  and  give  a 
little  jump  so  that  the  tip  of  one  of  its  front  paws  just  reached  the 
top,  and  then  pull  itself  up  with  the  greatest  ease.  When  it  is 
tired  of  playing,  it  climbs  on  my  lap  and  goes  to  sleep  quite  un- 
'disturbed  by  my  work  on  a  typewriter,  although  it  is  startled  by 
every  strange  noise.  It  uses  its  flat,  naked  palm  to  give  a  sharp 
rap  on  the  floor  or  on  the  surface  on  which  it  may  be  resting  when 
it  is  angry  or  excited  by  the  sight  of  a  strange  person  or  a  strange 
animal ;  but  this  is  also  a  call  note,  for  when  it  has  hidden  behind 
some  books  or  in  a  dark  corner,  it  comes  out  at  once  and  runs  to 
me  when  I  imitate  the  sound  it  makes.  The  fully  grown  hyrax 
can  defend  itself  well  by  giving  sharp  bites  with  its  long  incisor 
teeth.  My  little  animal,  which  is  able  to  give  quite  a  painful 
pinch  with  its  teeth,  has  learned  to  stop  when  I  say  "  No,"  and  to 
lay  hold  of  my  finger  quite  gently  ;  it  also  will  open  its  mouth 
when  I  tell  it  to  do  so.  Although  the  hyraxes  are  ungulates,  they 
stand  very  far  away  from  the  other  ungulates  and  are  probably 
as  nearly  related  to  the  ancestors  of  men  and  monkeys  as  to  the 
elephant  and  rhinoceros.  They  certainly  have  very  little  experience 
of  human  beings,  and  their  intelligence  and  capacity  for  being 
tamed  are  genuine  outcrops  of  their  constitution  and  habits. 

The  domestic  horse  and  donkey  have  been  subjected  to  so  many 
generations  of  breeding  that  their  qualities  may  be  taken  to  be  the 
result  of  man's  preference  rather  than  of  natural  disposition.  Young 
zebras,  zebra-donkey  and  zebra-pony  hybrids,  and  young  wild 
asses  of  every  kind  that  I  know  are  as  tame  and  gentle  and  affection- 
ate as  the  young  of  the  domesticated  races.  Like  these,  they 
readily  learn  to  know  their  keeper  and  to  follow  him  about,  and 
to  be  stroked  and  patted.  When  they  become  adult,  however, 
they  very  often  are  rather  savage  and  treacherous,  and  some  of  the 
wild  asses  are  amongst  the  most  dangerous  of  the  animals  that  are 
kept  in  captivity.  What  seems  to  have  happened  in  the  case  of 
the  horse  and  the  donkey  is  not  that  the  nature  of  the  young  has 


2i8  CHILDHOOD  OF  ANIMALS 

been  changed  by  domestication,  but  that  spirit  and  independence 
have  been  bred  out  of  the  race  by  getting  rid  of  the  adults  which 
showed  "  vice/'  the  name  that  we  apply  to  the  qualities  that  do 
not  suit  us.  Tapirs,  in  my  opinion,  are  stupid  and  rather  un- 
interesting animals.  The  young  follow  the  mothers  closely,  and 
parents  and  young  interchange  little  shrill  piping  noises.  Orphan 
young  tapirs  will  attach  themselves  to  a  keeper.  They  are  harmless, 
inoffensive  creatures,  but  as  they  grow  up  become  rather  shy  of 
human  beings.  Two  young  but  well-grown  Malay  tapirs,  which 
came  to  the  London  Zoological  Gardens  in  1912,  allowed  me  to 
handle  them,  to  rub  and  slap  their  backs  and  necks  the  first  time 
I  went  into  their  enclosure. 

The  relations  between  a  young  hippopotamus  and  its  mother 
are  intimate  and  long  continued.  I  have  seen  very  little  of  young 
hippopotami  and  nothing  at  all  of  baby  ones,  but  so  far  as  I  have 
been  able  to  find  out,  they  are  friendly  and  docile.  The  full-grown 
animals,  although  they  know  their  keepers  well,  are  not  to  be  trusted, 
and  if  given  the  chance,  would  charge  and  do  serious  injury.  The 
young  of  all  the  swine  and  of  the  peccaries  become  tame  almost 
at  once  and  show  great  affection  for  their  owners.  Young  peccaries, 
wart-hogs  and  river-hogs  have  often  been  brought  to  the  London 
Zoological  Gardens  by  persons  who  had  obtained  them  when  they 
were  mere  babies,  and  who  all  speak  with  delight  of  their  intelligence 
and  devotion.  As  they  are  powerful,  extremely  active,  and  able 
to  give  most  dangerous  wounds  when  they  are  full  grown,  familiarity 
with  them  is  generally  dropped  as  they  grow  up,  but  they  continue 
to  recognise  their  owners  and  to  show  pleasure  at  their  presence  for 
many  years. 

Although  camels  have  been  domesticated  for  so  long  that 
the  truly  wild  animal  is  unknown  to  exist,  they  have  never 
really  become  tame.  They  know  their  masters  and  obey  them 
within  limits,  but  most  of  them  are  ready  to  bite  at  any  time  and 
do  not  discriminate  between  friend  and  stranger.  Young  camels, 
certainly,  are  moderately  docile  and  show  some  cupboard  affection 
for  those  who  feed  them.  The  South  American  llama  and  alpaca 
have  been  domesticated  almost  as  long  as  camels,  but  are  less 
obstinate  and  more  gentle.  The  wild  forms  of  them,  the  small 
vicugna  and  the  larger  huanaco,  are  much  more  intelligent.  They 
are  extraordinarily  active,  rearing  on  their  hind-legs,  and  dancing 
in  the  most  curious  ways.  They  recognise  those  who  feed  them, 
and  the  single  males  of  each  species  now  alive  in  the  London 


THE  TAMING  OF  YOUNG  ANIMALS         219 

Zoological  Gardens  have  learned  to  recognise  an  individual  visitor 
both  by  her  voice  and  by  sight.  They  come  rushing  to  her  as  she 
approaches,  and  follow  her  to  the  front  or  the  back  of  the  enclosure, 
grunting  with  pleasure  and  offering  their  special  welcome  by  spitting 
at  her.  Both  of  these  are  dangerous  to  their  keepers.  The  vicugna 
was  brought  from  Patagonia  by  a  Fellow  of  the  Society,  who  had 
obtained  it  when  it  was  very  young  and  with  whom  it  was  quite 
tame  and  affectionate.  After  an  absence  of  more  than  a  year  this 
animal  recognised  and  welcomed  its  original  owner. 

The  fawns  of  all  wild  deer  and  the  young  of  all  wild  cattle,  sheep, 
goats  and  antelopes  readily  attach  themselves  to  man,  submitting 
to  a  good  deal  of  handling,  liking  to  be  petted,  recognising  their 
owners  and  readily  following  them.  Equally  I  think  they  are  all 
uncertain  when  they  are  adult,  the  males  at  the  breeding  season, 
and  most  of  them,  all  the  year  round.  There  are  differences  in 
temperament  which  are  not  easy  to  explain  and  which  do  not 
depend  on  size  or  on  habits,  and  of  which  the  young  show  no  trace. 
Thus  gnus  are  much  more  dangerous  and  ready  to  attack  their 
keepers  than  are  elands,  wild  sheep  are  more  combative  than 
wild  goats,  and  some  of  the  small  gazelles  and  small  deer  are  quite 
savage. 

I  have  little  personal  experience  of  young  rodents  except  of 
pet  rabbits,  which,  like  most  boys,  I  used  to  keep,  but  these 
have  been  so  debased  by  domestication  that  their  qualities  are 
not  interesting.  It  is  certain,  however,  that  the  young  of  all 
rodents  are  easily  tamed,  and  every  one  has  seen  or  heard  of  tame 
rats  and  mice,  hares,  dormice,  squirrels,  and  so  on.  They  recognise 
their  owners,  like  to  snuggle  against  them,  to  climb  on  them,  and 
readily  follow  them  about.  They  show  in  every  way  a  willingness 
to  accept  from  human  beings  the  attentions  they  would  naturally 
receive  from  their  mothers.  They  belong  to  the  set  of  animals 
which  on  the  whole  dislike  being  laid  hold  of,  and  which  are  disposed 
to  bite  any  one  who  tries  to  grasp  them,  but  are  much  more  often 
willing  to  climb  on  an  extended  hand  or  leg.  How  long  their  tame- 
ness  lasts  it  is  difficult  to  say.  We  get  a  good  many  presented 
to  the  Zoological  Gardens  because  they  have  begun  to  bite,  but  I 
suspect  that  in  some  cases  it  is  merely  because  their  owners  do 
not  pay  sufficient  attention  to  the  natural  disposition  of  which  I 
have  just  spoken.  We  are  too  ready  to  treat  all  tame  animals 
like  young  carnivores,  which  do  not  in  the  least  object  to  be  grasped 
and  picked  up  and  have  no  fear  of  being  held ;  but  most  animals, 


220  CHILDHOOD  OF  ANIMALS 

although  they  do  not  forcibly  resent  such  treatment  when  they 
are  very  young,  cease  to  submit  to  it  as  they  grow  older.  If  such 
animals  were  treated  with  a  due  respect  for  their  natural  disposi- 
tions, they  might  continue  to  be  quite  tame,  although  I  do  not 
think  that  they  have  sufficient  intelligence  or  memory  to  show  much 
difference  in  their  response  to  their  owners  and  to  strangers.  I 
have  seen,  however,  an  old  and  fully  grown  capybara,  the  largest 
of  living  rodents,  which  had  been  reared  on  a  private  estate,  and 
which  knew  its  owner  well  and  liked  coming  to  be  scratched  and 
fed  with  carrots  or  sugar,  and  I  have  been  told  of  adult  tame  beavers 
and  agoutis. 

Young  insectivores  such  as  moles,  hedgehogs  and  shrews  will 
attach  themselves  in  a  rather  stupid  mechanical  way  to  persons 
who  adopt  them,  and  certainly  like  nestling  in  a  warm  hand,  and 
understand  being  fed,  but  I  do  not  know  of  any  of  them  remaining 
really  tame  when  they  grow  up.  A  hedgehog  kept  in  a  garden 
will  become  accustomed  to  the  presence  of  human  beings  and  will 
usually  come  to  be  fed,  but  even  such  animals  stray  if  they  are 
given  the  opportunity.  I  have  been  unable  to  find  anything  about 
the  qualities  of  young  edentates.  Sloths  in  captivity  are  apathetic 
and  indifferent  rather  than  tame.  The  great  anteater  is  rather 
more  intelligent  and  certainly  distinguishes  between  strangers  and 
those  to  whom  it  is  accustomed,  but  armadillos  are  the  most  friendly 
of  all  the  edentates  that  I  have  seen  alive,  and  I  should  guess  that 
they  would  make  affectionate  and  fairly  intelligent  pets. 

All  the  marsupial  animals  have  a  relatively  low  intelligence,  and 
few  of  them  in  captivity  do  more  than  learn  not  to  be  afraid  of 
visitors  and  keepers  and  to  come  to  the  bars  to  be  fed.  By  the 
time  they  leave  the  mother's  pouch  permanently,  they  have  the 
mental  characters  of  the  adult,  and  I  do  not  know  of  any  case  where 
a  very  young  marsupial  has  been  removed  from  its  mother  and 
been  brought  up  by  hand.  The  larger  kangaroos  occasionally 
allow  themselves  to  be  handled,  and  some  of  the  small  nocturnal 
opossums  and  phalangers  submit  to  such  treatment  in  a  sleepy, 
indifferent  fashion.  The  thylacine,  or  striped  marsupial  wolf, 
and  the  Tasmanian  devil  become  gradually  accustomed  to  their 
keepers,  but  to  a  very  much  smaller  extent  than  in  the  case  of  the 
true  carnivores.  Their  intelligence  is  very  low,  and  they  remain 
shy,  suspicious  and  ready  to  bite. 

Young  animals  born  in  captivity  are  no  more  easy  to  tame  than 
those  which  have  been  taken  from  the  mother  in  her  native  haunts. 


THE  TAMING  OF  YOUNG  ANIMALS          221 

If  they  remain  with  the  mother,  they  very  often  grow  up  even  shyer 
and  more  ntolerant  of  man  than  the  mothers  themselves.  There 
is  no  inherited  docility  or  tameness,  and  a  general  survey  of  the 
facts  fully  bears  out  my  belief  that  the  process  of  taming  is  almost 
entirely  a  transference  to  human  beings  of  the  confidence  and 
affection  that  a  young  animal  would  naturally  give  its  mother. 
The  process  of  domestication  is  different,  and  requires  breeding 
a  race  of  animals  in  captivity  for  many  generations,  and  gradually 
weeding  out  those  in  which  youthful  tameness  is  replaced  by  the 
wild  instincts  of  adult  life,  and  so  creating  a  strain  with  new  and 
abnormal  instincts. 

Apart  from  whether  or  no  it  lasts  after  a  young  animal  has  grown 
up,  the  degree  to  which  tameness  can  be  carried  depends  on  the 
natural  habits  of  the  animals  concerned,  on  their  intelligence  and 
on  their  inborn  instincts.  Taming  should  be  no  more  than  taking 
advantage  of  the  natural  instincts  and  guiding  them  in  a  slightly 
new  direction.  It  is  quite  true  that  animals  of  high  intelligence 
can  be  trained  to  do  many  things  entirely  outside  their  natural 
range.  If  the  animals  have  good  memories  and  their  trainer  use 
punishment  freely,  he  can  produce  remarkable  results,  but  I  cannot 
understand  how  persons  who  think  that  they  are  fond  of  animals 
can  endure  seeing  most  of  these  tricks.  A  chimpanzee  in  evening 
dress,  lighting  a  cigarette  and  drinking  brandy-and-soda  on  a 
music-hall  stage  is  a  shameful  abuse  of  man's  power  over  the  ape's 
docility.  Lions,  tigers  and  polar  bears  snarling  in  a  pyramid, 
with  the  whip  cracking  and  the  iron  bar  and  loaded  pistol  ready 
to  the  hand  of  their  trainer,  can  amuse  only  very  stupid  people,  and 
the  performance  is  probably  less  dangerous  than  sword-swallowing. 


CHAPTER  XIV 
THE  PURPOSE  OF  YOUTH 

ALTHOUGH  it  was  not  my  intention  in  writing  this  book  or  in  prepar- 
ing the  lectures  on  which  it  was  founded  to  construct  a  carefully 
considered  and  elaborate  argument,  I  have  tried  to  develop  a  general 
idea  and  to  illustrate  it  by  selecting  appropriate  instances  from 
the  abounding  variety  of  nature.  The  period  of  childhood  or  youth 
is  peculiar  to  the  living  world  and  occurs,  in  the  first  place,  merely 
because  most  living  things  do  not  come  into  existence  as  fully 
formed  creatures  like  their  parents,  but  as  little  specks  of  living 
matter  much  more  like  the  earliest  forms  of  life  that  existed.  It 
has  taken  countless  centuries  for  the  living  species  of  animals  and 
plants  to  evolve  from  the  primitive  forms  of  living  beings,  and  yet 
in  each  generation  each  new  individual  has  to  repeat  the  prodigious 
process  of  changing  from  the  minute  cell  known  as  the  egg-cell, 
which  is  separated  from  the  tissues  of  its  parent,  to  the  complicated 
adult  body,  often  composed  of  myriads  of  cells,  with  different  struc- 
tures and  functions,  and  built  up  into  the  elaborate  architecture 
of  the  adult.  One  of  the  little  grains,  of  which  you  see  thousands 
in  the  hard  roe  of  a  herring,  would  presently  have  been  shed  into 
sea-water,  met  and  fused  with  another  little  speck  of  matter,  but 
so  small  that  you  cannot  distinguish  it  without  the  aid  of  a  micro- 
scope, from  the  soft  roe  of  another  herring,  would  have  absorbed 
moisture  and  oxygen  from  the  sea-water,  and  would  have  grown 
visibly  bigger,  until  presently  it  burst  and  gave  birth  to  a  minute 
fish-like  creature  still  very  unlike  a  herring.  This  tiny  transparent 
living  thing  would  have  fed  eagerly  on  still  tinier  specks  of  living 
matter  in  the  water,  and  in  course  of  time,  if  it  itself  escaped  being 
eaten,  would  have  turned  to  a  swift  and  scaly  fish,  with  a  brain 
and  muscles,  gills  and  red  blood.  The  egg  of  a  hen  would  seem 
to  have  a  task  that  is  a  little  easier,  for  the  little  speck  of  living 
matter  inside  the  eggshell  is  packed  round  and  round  with  rich 
food,  but  the  transformation  of  the  liquid  stuff  that  we  see  when 
we  break  open  a  new-laid  egg  into  the  warm  and  feathered,  hungry 

222 


THE  PURPOSE  OF  YOUTH  223 

and  piping  chick  that  breaks  through  the  shell,  is  a  marvellous 
prodigy.    That  these  changes  should  happen  at  all  seems  so  miracu- 
lous that  perhaps  it  would  not  be  more  surprising  if  they  happened 
instantaneously.      It  may  be  unphilosophical  to  expect  it,  but  at 
least  it  is  more  comfortable  to  our  intelligence  that  the  growth 
of  the  individual  does  take  time.     When  the  details  of  the  process 
are  studied  minutely,  they  are  found  to  be  gradual  and  orderly  ; 
the  initial  piece  of  living  matter  grows  and  divides,  and  the  daughter- 
pieces  divide,  much  in  the  manner  of  free-living  cells  which  are  not 
going  to  transform  themselves  into  more  complicated  creatures. 
The  first  set  of  daughter-cells  becomes  arranged  in  a  fashion  closely 
resembling  the  structure   of  simple,  living  creatures  which  do  not 
proceed  beyond  such  a  stage,  and  so,  step  by  step,  with  at  each  step 
a  memory  more  or  less  definite  of  some  free-living  creature  that 
proceeds  no  further,  the  final  complication  of  the  new-born  or  new- 
hatched  young  is  reached.     Again,  it  may  be  unphilosophical,  but 
it  is  comfortable  to  our  intelligence,  to  recognise  that  the  growth 
of  the  individual  is  a  faint  reflection  of  the  path  of  its  ancestors 
in  the  long  evolution  of  life.     The  later  phases  of  the  development 
of  the  individual,  those  that  are  passed  through  after  it  is  hatched 
or  born,  are  not  different  in  kind  from  the  earlier  or  embryonic  stages. 
And  so  we  come  to  see  at  least  without  surprise,  if  with  less  real 
understanding  than  we  are  philosophically  justified  in  claiming, 
that  living  things  pass  through  a  period  of  childhood  or  youth, 
and  that  that  period  is  filled  with  memories  of  ancestral  history. 

In  the  development  of  many  animals  these  memories  of  the  past, 
in  embryonic  and  in  larval  stages,  and  in  the  period  of  youth,  are 
sometimes  so  precise  and  definite  that  they  seem  to  give  a  clear 
picture  of  at  least  part  of  the  ancestral  history.  Such  instances 
are  most  common  in  the  lower  animals  and  in  the  lower  members 
of  the  higher  classes.  They  tend  to  be  blurred  and  condensed, 
or  omitted  altogether.  It  seems,  in  fact,  as  if  the  first  object  of 
nature  were  to  get  rid  of  evidence  of  past  evolution,  and  to  hurry 
through  each  new  creature  as  quickly  and  directly  as  possible  to 
its  adult  form. 

Youth  is  a  perilous  time  in  the  life  of  animals.  The  young  things, 
with  their  imperfect  organs,  with  their  relics  of  stages  that  were 
fitted  to  the  environment  of  a  remote  ancestor,  but  are  out  of  gear 
with  existing  conditions,  are  hampered  with  the  cumbrous  scaffolding 
of  the  past  and  can  offer  feeble  resistance  to  accidents  and  diseases. 
They  are  a  ready  prey  for  a  world  of  hungry  enemies.  It  is  in  the 


224  CHILDHOOD  OF  ANIMALS 

first  place  imperative  that  this  period  of  feebleness  should  be  passed 
through  as  quickly  as  possible.  And  evidence  of  a  tendency  to 
shorten  and  simplify  the  development  of  the  embryo  or  of  the 
larva,  to  remove  all  stages  that  have  ceased  to  be  useful  and  to 
make  straight  the  path  from  egg  to  adult  is  to  be  found  in  every 
group  of  the  animal  kingdom,  but  is  increasingly  plain  in  the  higher 
groups  and  the  higher  members  of  every  group. 

The  shortening  and  simplification  are  most  complete  in  the  em- 
bryonic stages  of  development,  whether  these  take  place  within 
an  eggshell  or  in  the  body  of  the  mother.  In  free-living  larvse, 
or  in  active  young,  protection  is  often  obtained  by  new  organs, 
special  habits,  peculiar  pattern  and  coloration  that  may  have  no 
reference  to  the  past  history  of  the  animal  and  no  direct  bearing 
on  its  adult  shape  and  form.  Larval  organs,  habits  and  coloration 
are  not  infrequently  new  interpolations  in  the  life-history,  the  sole 
purpose  of  which  is  to  protect  the  larvae  and  give  them  a  chance 
of  coming  to  maturity.  I  confess  that  when  I  was  beginning  to 
collect  materials  about  young  animals,  I  hoped  to  find  that  youthful 
characters  would  sometimes  show  the  direction  in  which  the  race 
might  be  supposed  to  be  going  to  develop.  I  thought  that  I  should 
find  the  exuberant  vitality  of  youth  displaying  itself  in  new  ways, 
some  of  which  might  turn  out  to  be  useful  and  come  to  be  adopted 
by  the  adult.  I  can  find  no  trace  of  such  prophetic  or  tentative 
efflorescence  in  structure,  coloration  or  pattern,  although,  as  I 
shall  show  later,  there  is  something  comparable  with  it  in  the  mental 
qualities  of  youth.  The  physical  characters  of  youth  are  sternly 
economic.  Special  organs,  new  or  old,  are  present  because  they 
make  it  more  possible  for  the  creatures  to  escape  the  destruction 
that  is  always  treading  on  the  heels  of  the  young.  Pattern  and 
coloration  are  either  simply  the  ancestral  garb  of  the  parents  still 
retained,  or  the  direct  results  of  growth,  or  occasionally,  and  especially 
in  caterpillars,  devices  for  the  immediate  protection  of  the  young. 
The  youth  of  most  animals  is  too  hampered  by  the  past,  too  harassed 
by  the  present,  for  experiment  in  structure  or  coloration  to  be 
possible. 

The  amazingly  heavy  mortality  that  presses  on  the  young  is 
met  in  a  great  many  cases  by  the  enormous  size  of  the  families.  I 
have  given  instances  of  the  almost  incredible  number  of  eggs  that 
are  laid,  of  young  animals  that  are  turned  adrift,  a  few  of  which 
escape  the  perils  that  beset  them  and  live  to  maintain  the  species. 
This  spendthrift  fashion  of  reproduction,  which  bears  witness  to 


THE  PURPOSE  OF  YOUTH  225 

the  prodigality  of  Nature  rather  than  to  her  inventiveness,  is 
gradually  replaced  by  a  new  method.  The  number  of  the  young 
is  very  greatly  reduced,  and  the  small  families  are  protected  by 
the  parents.  Sometimes  the  eggs  are  retained  in  the  body  of  the 
mother  until  they  are  nearly  ready  to  hatch  ;  sometimes  they 
hatch  within  her  body  and  are  fed  from  her  blood  ;  sometimes 
even  the  eggshell  is  dispensed  with,  and  from  the  earliest  appearance 
of  the  embryo  as  a  separate  speck  of  living  matter,  it  is  fed  from 
the  blood  of  the  mother.  The  eggs  may  be  laid  in  places  carefully 
prepared  by  the  mother  or  by  both  parents,  and  eggs  and  young 
may  be  fed  and  guarded  for  long.  The  young,  even  if  born  in  an 
active  condition,  may  be  fed  and  protected  by  the  parents  for  years 
or  months.  Instead  of  hundreds  of  thousands  of  helpless  young 
dumped  on  a  careless  and  hostile  world,  a  very  small  number, 
sometimes  only  a  single  individual,  is  produced  at  a  time  and  cared 
for  in  the  most  complete  fashion. 

In  the  highest  animals,  and  especially  in  mammals,  the  young 
are  freed  from  the  trouble  of  finding  their  own  food  ;  they  have  very 
seldom  to  defend  themselves,  and  the  changes  from  egg  to  embryo 
and  from  embryo  to  adult  are  made  as  simple  and  direct  as  possible, 
and  none  the  less  the  duration  of  the  period  of  youth  increases  as  we 
go  up  the  scale  of  animal  life.  This  lengthening  of  youth  is  specially 
plain  when  we  compare  the  different  members  of  a  single  group. 
If  we  take  the  human  race  and  its  allies,  the  apes,  monkeys  and 
lemurs,  then  man,  who  is  at  the  top  of  the  scale,  has  the  longest 
youth,  and  even  in  the  lower  and  less  civilised  races,  it  would  be 
'unsafe  to  assign  less  than  fifteen  years  to  immaturity,  whilst  in 
the  higher  and  more  civilised  types  it  is  still  longer.  The  great 
apes,  the  gorilla,  orang  and  chimpanzee,  take  from  eight  to  twelve 
years  to  grow  up.  The  baboons  and  common  monkeys  take  from 
three  to  eight  years,  and  the  little  South  American  monkeys  and 
lemurs  require  only  two  to  three  years.  If  we  take  weight  or 
stature  of  the  body,  the  strength  of  the  muscles  or  any  of  the  purely 
physical  qualities,  we  shall  find  that  they  do  not  fit  this  varying 
scale  of  youth.  There  is  only  one  part  of  the  body  that  can  be 
reconciled  with  it. 

In  the  figures  (Fig.  36)  I  show  the  contour  of  the  brain  in  a  set  |; 
of  primate  animals  drawn  roughly  to  scale.      It  will  be  seen  at  I 
once  that  man,  with  the  longest   period  of  youth,  has  the  largest  | 
brain  ;  that  although  a  chimpanzee  may  equal  or  exceed  a  man 
in  size  and  weight,  its  brain  is  much  smaller ;  and  that  the  brain 

C.A.  P 


226  CHILDHOOD  OF  ANIMALS 

of  a  macaque  is  still  smaller,  but  larger  than  that  of  a  cebus 
monkey.  It  is  better  not  to  include  lemurs  in  this  series. 
Although  they  are  more  closely  related  with  apes  and  monkeys  than 
with  any  other  living  animals,  they  form  an  independent  series,  the 
lowest  members  of  which  have  smooth  and  small  brains,  yet  the 
higher  members  of  which  have  brains  which  surpass  in  develop- 
ment those  of  the  lowest  monkeys. 

But  there  is  a  more  important  consideration  even  than  size. 
The  cerebrum,  the  great  mass  of  the  brain  that  fills  most  of  the 
hollow  of  the  skull,  is  smooth  in  the  lowest  forms  save  for  a  few  faint 
wrinkles,  which  become  more  conspicuous  and  more  numerous 
successively  in  the  cebus,  macaque  and  chimpanzee,  until  they 
attain  the  high  complexity  shown  in  the  human  brain.  The  corre- 
spondence is  so  close  that  we  may  say  almost  definitely  that,  at  least 
inside  the  great  groups  of  mammals,  the  length  of  the  period  of 
youth  increases  with  the  size  and  complexity  of  the  brain. 

Without  going  too  deeply  into  anatomical  details,  we  can  take 
the  comparison  a  little  further.  If  a  slice  cut  through  a  cerebrum 
be  examined  even  with  the  naked  eye,  it  will  be  seen  to  consist  of 
a  greyish  layer,  closely  following  the  external  contour,  and  a  deeper- 
seated  white  mass.  If  you  compare  two  stretches  of  coast  occupying 
roughly  the  same  space  on  a  map,  as,  for  instance,  the  east  coast 
of  Wicklow  and  Wexford  with  the  south-west  coasts  of  Kerry  and 
Cork,  you  will  see  at  once  that  the  coast-lines  corresponding  with 
the  same  inland  area  may  differ  enormously  in  length,  according 
to  whether  they  present  an  even  front  to  the  sea,  or  are  twisted 
into  bays  and  fiords.  So  also  in  brains  of  nearly  the  same  size, 
the  amount  of  grey  matter  is  much  greater  in  one  that  is  folded 
and  convoluted  than  in  one  that  is  nearly  smooth.  The  duration 
of  youth  in  animals  belonging  to  the  same  group  varies  with  the 
relative  amounts  of  grey  matter  contained  in  their  brains. 

I  am  not  going  to  discuss  here  whether  the  brain  be  an  organ  of 
the  mind,  played  on  by  some  immaterial  entity,  as  a  musician  plays 
on  a  musical  instrument,  or  whether  mental  qualities  be  emanations 
of  the  brain  as  bile  is  a  secretion  of  the  liver.  It  is  enough  that 
the  mental  powers  are  definitely  associated  with  the  grey  matter, 
and  that  their  development  and  education  write  a  record  upon  it. 
The  grey  matter  contains  the  nerve-cells  of  the  brain.  A  fully 
developed  nerve-cell  may  be  compared  with  a  spider  seated  in  the 
centre  of  a  web  which  is  an  actual  set  of  outgrowths  from  itself, 
.Some  of  the  fibres  of  the  web  are  in  connection  with  nerves  ;  indeed, 


THE  PURPOSE  OF  YOUTH 


227 


there  are  continuous  fibres  from  the  cells  in  the  brain  to  the  remotest 
tissues  of  the  body.  Other  fibres  are  continued  to  the  web-fibres 
of  other  brain-spiders.  The  sys- 
tem might  be  compared  with  a 
very  complicated  set  of  telephone 
exchanges,  each  exchange  supply- 
ing a  certain  district  near  at  hand 
or  far  away,  and  each  linked  up 
with  a  number  of  other  exchanges 
with  their  districts.  The  greater 
the  number  of  subscribers'  wires 
to  each  exchange  and  the  greater 
the  number  of  connections  with 
other  exchanges,  the  more  perfect 
the  system  would  be. 

The  details  of  the  development 
of  the  brain  are  difficult  and 
obscure,  but  there  is  a  good  deal 
of  evidence  to  show  that  the  actual 
number  of  brain-cells  does  not 

increase  during  childhood,  youth, 

or  adult  life.     The  initial  number 

of  cells  may  be  taken  as  an  index 

or  physical  correlate  of  the  natural 

endowment.    Species  or  indi- 
viduals with  many  of  them 

in  a  given  area  have  a  richer 

potentiality  of   mental  life. 

In  the  new-born    mammal, 

however,   large  numbers    of 

the   brain-cells    lie    isolated 

and  quiescent    in    the   grey 

matter  ;  they  are  joined  up 

neither  to  each  other  nor  to 

distant   parts  of  the   body. 

In  early  infancy  the  brain 

has  little  or  no  control  over 

even    the    chief   muscles  and  FIG.  36.      Brains   of    Primates.      The  largest 

f  ,,       ,      ,           „„.     .  (lowest   figure)   is  human;    next,  that    of 

tissues  OI  the  body*       1  ills  IS  a   chimpanzee;    next,  that  of  a  macaque 

probably  the   explanation    of  monkey;    next    (uppermost    figure),    that 

r               J                                          .  of  a   cebus  monkey.     (The  figures  are  all 

a    famous   observation  much  reduced  to  the  sarne  scale. ) 


228  CHILDHOOD  OF  ANIMALS 

written  about  some  years  ago.     It  is  known  that  at  least  some  very 
young  infants  will  seize  firmly  any  object  which  they  can  grasp.     If 
one  be  given  a  broom-handle  of  which  to  lay  hold,  it  will  swing  from 
this  by  one  hand  or  by  both  hands,  and  even,  by  bending  the  muscles 
of  the  arms,  pull  itself  up.     When  a  little  older  an  infant  is  unable 
to   do   this.      The    suggestion  was   that   in  its  extreme  infancy 
the  young  human  being  showed  this  sign  of  its  monkey  ancestry 
and  swung  from  the  broom-handle  as  an  ape  would  swing  from 
the  branch  of  a  tree.     The  objection  was  taken  to  such  an  interpreta- 
tion that  the  action  of  the  young  infant  was    purely  automatic, 
that  its  brain-cells  were  not  yet  joined  up  to  the  lower  centres  which 
control  the  automatic  movements  of  the  body.     A  frog  the  cerebrum 
of  which  has  been  destroyed,  if  placed  in  a  bowl  of  water,  will  go 
on  swimming  indefinitely  until  it  dies  of  exhaustion.     The  contact 
of  water  with  the  skin  makes  the  direct  and  automatic  suggestion 
to  the  lower  nerve-centres  which  control  the  operation  of  swimming, 
whilst  if  the  brain  were  intact,  sensations  of  hunger,  of  weariness, 
of  desire  to  escape  and  so  forth  would  have  come  into  play  and 
caused  a  change  in  the  movement.     The  young  infant  is  a  brainless 
creature,  because  the  nerve-cells  of  its  cerebrum  are  not  yet  linked 
up  with  the  rest  of  the  body.     On  this  view,  however,  the  comparison 
really  becomes  more  interesting.     The  infant  swinging  from  the 
broomstick  is  not  acting  like  full-grown  apes,  but  like  young  apes 
clinging  to  their  mother.     A  new-born  leopard,  or  mole,  or  hedgehog 
would  not  cling  to  a  broomstick  in  this  way,  but  a  new-born  ape 
or  monkey  does  so.    The  automatism  lasts  longer  in  the  ape  than 
in  man  and  is  less  interfered  with  by  the  suggestions  coming  from 
the  brain,  as  throughout  life  there  are  fewer  brain-cells  and  these 
have  less  complete  junctions  with  each  other  and  with  the  lower 
centres.     There  are  many  cases  in  the  adult  life  of  human  beings 
where  the  higher  cells  or  some  of  them  are  temporarily  thrown  out 
of  action,  so  that  they  are  in  the  same  position  as  if  they  had  ceased 
to  be  joined  up.     And  in  such  cases  the  behaviour  of  the  patient 
recalls  that  of  apes  and  monkeys.     When  a  normal  healthy  human 
being  is  struggling  or  fighting  with  persons  trying  to  seize  him,  he 
uses  only  a  small  part  of  his  muscular  power,  because  the  higher 
centres  of  the  brain  are  interfering  and  warning  him  that  he  has  to 
take  care  of  himself,  to  avoid  being  hurt  and  even  to  avoid  hurting 
his  opponents  too  much.     But  if  he  be  mad,  if  some  of  the  higher 
brain-cells  are  temporarily  put  out    of    action,  then  he  loses  all 
restraint,  and  fights,  as  a  desperate  animal  fights,  without  any 


THE  PURPOSE  OF  YOUTH  229 

thought  of  his  own  safety,  and  so  exercises  much  more  than  his 
ordinary  strength.  The  events  of  some  cases  of  somnambulism  are 
still  more  remarkable  examples  of  what  happens  when  the  higher 
cells  of  the  brain  are  temporarily  shut  off  from  their  control.  Metch- 
nikoff  has  collected  a  number  of  cases  in  which  persons  in  the  condi- 
tion of  somnambulism  performed  with  sureness  and  agility  feats 
such  as  running  up  and  down  the  steep  roofs  of  houses,  climbing 
to  places  that  they  could  not  have  reached  and  where  they  certainly 
would  not  have  retained  their  balance  had  they  been  in  the  normal 
condition.  He  suggests  that  these  are  real  returns  to  the  automatic 
fearlessness  and  semi-conscious  gymnastics  of  the  great  apes. 

The  period  of  youth  in  mammals  is  the  time  when  the  brain-cells 
of  the  superficial  grey  matter  increase  in  size,  throw  out  fibres, 
and  come  into  more  and  more  complex  connection  with  each  other 
and  with  the  different  systems  of  the  body.  Just  as  the  number 
of  these  cells  forms  an  index  of  the  natural  endowment  of  an 
animal,  so  the  extent  to  which  these  interconnections  are  developed 
is  a  measure  of  the  effect  of  education,  in  the  widest  sense  of  the 
word.  An  animal  with  a  smaller  natural  endowment  might  reach, 
by  a  greater  development  of  the  initial  stock,  a  higher  mental  plane 
than  another  animal  with  many  more  cells  that  had  remained 
quiescent.  No  doubt  a  certain  amount  of  development  of  these 
cells  takes  place  throughout  the  whole  period  of  life,  particularly 
in  the  higher  and  more  intelligent  animals.  But  even  in  human 
beings,  at  least  in  average  cases,  there  appears  to  be  comparatively 
little  further  change  in  female  brains  after  the  age  of  fifteen,  and 
in  male  brains  after  that  of  twenty-four  or  twenty-five.  In  animals, 
which  after  they  have  come  to  maturity  seldom  change  the  cha- 
racter of  their  experiences  or  of  their  abilities  much,  it  is  probable 
that  the  growth  of  the  processes  of  the  brain-cells  practically  is 
limited  to  the  period  of  youth.  We  may  in  fact  say  more  definitely 
that  the  period  of  youth  is  necessary  for  and  is  occupied  by  the 
co-ordination  of  the  brain-cells  of  the  grey  matter  and  the  develop- 
ment of  a  greater  complexity  of  the  intercommunications  of  these. 

We  are  on  safer  ground t  however,  when  we  turn  from*  the  physical 
mechanism  of  the  mind  to  the  mental  qualities  themselves^  and 
consider  the  effect  of  education  on  these,  without  too  nice  an  inquiry 
as  to  what  is  education  of  the  body  and  what  is  education  of  the 
mental  qualities.  We  like  to  think  that  animals  have  instinct  and 
that  we  have  intelligence,  but  the  passage  from^one  to  the  other  is 
gradual.  All  instinct  can  be  modified  to  a  certain  extent  by  expe- 


230  CHILDHOOD  OF  ANIMALS 

rience,  and  there  remains  a  strong  instinctive  side  in  intelligence. 
The  modifications  of  instinct  may  last  only  a  very  short  time  or 
they  may  remain  almost  permanent.  They  may  be  not  much 
more  than  purely  mechanical  changes,  as  when  a  new  pen  after  a 
little  use  writes  more  smoothly,  or  the  other  kind  of  change  that 
is  known  as  fatigue,  as  when  a  watch-spring,  repeatedly  used, 
must  be  allowed  a  rest  to  recover  its  normal  reaction.  From  these 
simple  changes  the  effects  of  experience  on  instinct  grade  up  towards 
memory,  and  at  least  in  human  beings  into  conscious  memory. 
The  period  of  youth  is  the  time  when  instinct  is  gradually  broken 
down  and  replaced  by  experimental  action. 

Let  us  get  the  matter  clear  by  some  examples  of  undoubted 
instinct.  A  caterpillar  is  developed  from  an  egg  laid  on  a  leaf. 
It  has  never  seen  its  mother.  It  has  never  done  anything  all 
through  its  life,  except  eat  when  it  was  hungry  (and  that  was  most 
of  the  time),  crawl  under  the  leaf  when  it  rained,  come  out  again 
and  resume  eating  when  it  was  dry,  and,  perhaps,  when  it  was 
startled,  drop  suddenly  down,  spinning  a  thread  of  silk,  by  which 
it  re-ascended  after  a  time.  Suddenly,  and  once  only  in  its  lifetime, 
it  completely  changes  its  habits.  It  spins  silk  without  having 
been  disturbed,  rolls  itself  up  in  a  leaf  and  fastens  the  edges  of 
this  blanket  with  threads  of  silk.  All  the  caterpillars  in  the  same 
brood  do  this  exactly  in  the  same  way  and  almost  exactly  at  the 
same  time.  They  either  accomplish  their  task  correctly  or  bungle 
it  completely.  There  is  no  question  of  practice,  or  imitation,  or 
of  learning.  The  necessary  act  is  accomplished  once  and  for  all. 
When  I  was  at  Oxford,  I  used  to  keep  common  garden  spiders 
in  a  cage,  and  found  that  when  they  were  provided  with  twigs  and 
proper  surfaces  to  which  they  could  attach  the  anchoring  spokes 
of  their  webs,  they  spun  these  always  exactly  in  the  same  way,  and 
that  in  watching  them  the  action  seemed  so  orderly  and  was  so 
completely  fitted  for  its  object  that  it  was  difficult  not  to  think 
of  it  as  intelligent.  But  one  of  the  spiders,  placed  under  an  inverted 
bell- jar  to  which  the  threads  would  not  remain  fastened,  quite 
contentedly  went  through  the  exact  routine  of  operations  for  making 
a  web,  although  the  result  was  a  meaningless  wisp  of  threads.  A 
chick  that  has  been  blinded  by  covering  its  eyes  with  a  hood  almost 
before  it  has  got  out  of  the  shell,  and  that  is  kept  blindfolded  and 
fed  by  hand  for  a  day  or  two  until  it  is  strong,  will  peck  at  objects 
unerringly  as  soon  as  it  is  allowed  to  see  them,  although  it  will  not 
at  once  distinguish  between  food  and  stones.  My  caracal  cub 


THE  PURPOSE  OF  YOUTH  231 

was  taken  from  its  mother  when  it  was  just  able  to  see,  and  not 
nearly  strong  enough  to  stand  upright  on  its  legs.  It  was  born 
very  early  in  the  year,  in  what  turned  out  to  be  a  cold  spring,  and 
for  at  least  three  months  it  had  no  opportunity  of  seeing  either 
another  caracal,  or  even  any  kind  of  cat.  It  lived  entirely  with 
human  beings.  It  was  accustomed  to  be  washed  and  brushed  care- 
fully, and  yet  as  soon  as  it  was  strong  enough,  it  began  to  lick  its 
own  paws,  to  wet  them  and  use  them  to  wash  its  face,  precisely 
in  the  fashion  of  its  parents  and  of  all  their  ancestors  and  of  the 
whole  tribe  of  cats  from  time  immemorial.  It  is  easy  to  misin- 
terpret instincts  and  to  think  of  them  as  intelligent,  or  as  meaning 
more  than  they  do.  A  well-known  naturalist  has  related  that  once 
he  passed  straight  from  stroking  his  dog  to  a  litter  of  kittens  two 
'days  old  and  still  blind.  As  soon  as  he  touched  them,  the  tiny 
things  began  to  hiss  and  spit,  and  he  explained  this  as  an  instance 
of  the  instinctive  enmity  of  cats  for  dogs.  But  this  was  reading 
too  much  into  it.  The  spitting  of  the  kittens  was  a  generalised 
reaction  to  sudden  disturbance.  Young  ocelots,  leopards  or  caracals 
will  hiss  and  spit  at  any  unknown  touch  or  smell.  In  a  beautiful 
passage  in  one  of  his  plays,  M.  Francois  de  Curel  describes  some 
one  watching  rats  playing  in  the  moonlight  in  a  courtyard  shadowed 
by  plane-trees.  Suddenly  a  large  leaf  flutters  down  from  a  bough 
and  the  scared  rats  bolt  in  every  direction.  You  are  not  to  laugh 
at  them  and  think  of  them  as  silly,  being  scared  by  a  shadow.  The 
plane  leaf  might  have  been  some  nocturnal  bird  of  prey,  and  the 
rat  that  waited  to  investigate  the  danger  would  not  have  lived  to 
benefit  by  the  experience  it  had  gained. 

Instincts,  whether  they  are  complicated,  like  the  spinning  of  a 
web,  or  simple,  like  the  sudden  response  to  a  disturbance,  have  not 
to  be  learned  and  imply  neither  intelligence  nor  consciousness. 
They  either  fit  a  very  precise  set  of  conditions,  and  if  these  are  not 
present  they  break  down,  or  they  are  so  vague  and  generalised  that 
they  are  not  easy  to  distinguish  from  processes  with  which  the 
brain  has  nothing  to  do.  If  an  unpleasant  substance  such  as  an 
acid  be  applied  to  the  leg  of  a  frog,  it  will  pull  the  leg  away  ;  if  the 
leg  be  held,  it  will  apply  the  other  leg  to  the  affected  spot,  and  try 
to  rub  the  acid  off.  Such  behaviour  we  certainly  regard  as  a 
simple  kind  of  protective  instinct,  but,  as  it  takes  place  as  precisely 
in  a  frog  which  has  had  its  cerebrum  destroyed  as  in  an  undamaged 
animal,  probably  all  such  instincts  are  combinations,  more  or  less 
complicated,  of  the  direct  physical  responses  to  stimulation  which 


232  CHILDHOOD  OF  ANIMALS 

living  matter  displays.  To  analyse  them  into  their  constituent 
parts  is  a  kind  of  vital  chemistry  still  beyond  our  power,  and  it  is  still 
more  difficult  to  understand  the  complex  results,  arising  from  their 
combinations  in  different  proportions,  than  it  is  for  us  to  understand 
how  it  is  that  when  hydrogen  and  oxygen  are  combined  in  a  particu- 
lar proportion,  the  qualities  of  the  resulting  water  are  so  different 
from  the  qualities  of  the  two  elements.  Still  less  do  we  understand, 
although  we  know  that  it  must  exist,  the  physical  machinery  by 
which  these  complex  inborn  instincts  are  worked  and  transmitted 
from  parent  to  offspring. 

A  few  examples  of  some  of  the  simpler  elements  out  of  which  the 
instincts  are  combined  may  make  this  difficult  subject  clearer. 
They  are  what  are  known  as  tropisms,  tendencies  to  turn  towards, 
or  to  turn  away  from,  the  source  of  physical  stimulation,  and  are 
found  in  all  kinds  of  living  matter,  animal  or  vegetable.  They 
may  be  traced  upwards  to  the  most  highly  developed  of  living 
beings,  including  ourselves,  although  in  these  latter  they  may  be 
disguised  or  controlled  by  the  higher  nerve-centres.  The  reaction 
to  light  is  known  as  phototropism  or  phototaxis.  Many  free-living 
cells,  especially  the  swarm-spores  of  plants,  diatoms,  and  even 
many  colourless  animal  and  vegetable  organisms  move  in  the  direc- 
tion of  illumination,  if  the  light  be  not  too  strong,  but  on  over- 
stimulation  may  move  away  from  it.  Other  small  organisms 
move  away  from  light  towards  darkness  under  all  circumstances. 
In  some  of  the  compound  organisms  this  reaction  to  light,  positive 
or  negative,  may  be  shown  by  the  direction  of  growth  rather  than 
of  locomotion,  as  when  the  shoot  of  a  plant  bends  towards  the  light, 
or  its  rootlet  on  emergence  from  the  seed-capsule  bends  away  from 
it,  and  some  of  the  plant-like  compound  polyps  show  precisely 
similar  reactions.  Hydra  bends  towards  light,  some  small  worms 
move  towards  it  and  others  away  from  it.  From  these  simple 
reactions,  we  pass  by  easy  transitions  to  the  much  more  complicated 
and  yet  more  precise  actions  of  the  higher  animals  with  eyes  and 
with  definite  nervous  systems.  Turn  up  a  stone  on  the  seashore 
or  a  log  of  wood  in  a  garden,  and  you  will  see  numberless  little 
creatures  disturbed  by  their  exposure  to  light  and  at  once  setting 
about  wriggling,  creeping  or  running,  until  they  can  get  to  darkness 
again.  The  reaction  begins  before  there  is  any  trace  of  a  definite 
mechanism  to  produce  it,  and  is  continued  up  to  those  animals  to 
which  even  persons  least  inclined  to  assent  to  the  existence  of  con- 
sciousness in  all  living  matter  are  quite  ready  to  attribute  some 


THE  PURPOSE  OF  YOUTH  233 

form  of  consciousness.  Very  low  in  the  series,  too,  we  see  the 
simple  reaction  changing  with  the  state  of  the  creature  to  which 
it  is  applied,  the  turning  towards  light,  for  instance,  being  reversed 
to  a  turning  away  from  it,  when  the  stimulation  reaches  a  certain 
degree  of  intensity.  And  so  long  before  the  dawn  of  consciousness, 
unless  the  term  consciousness  be  so  attenuated  as  to  be  meaningless, 
we  get  a  beginning  of  adaptive  response. 

The  contact  tropisms  are  other  factors  of  instinct  at  first  extremely 
simple.  A  free-swimming,  single-celled  creature,  animal  or  plant, 
which  comes  in  contact  with  an  obstacle,  responds  in  some  way. 
It  may  shrink  back,  sometimes  with  a  little  turning  movement, 
and  advance  again,  and  ft  may  proceed  by  this  system  of  trial  and 
error  until  it  finds  a  way  round.  On  the  other  hand,  if  an  amoeba 
come  across  a  solid  surface,  it  at  once  creeps  out  over  it,  for  it  is 
the  habit  of  that  creature  to  creep  in  contact  with  any  flattened 
surface,  instead  of  drifting  freely  in  the  mud  or  water.  A  growing 
rootlet  burrows  into  every  crevice,  whilst  a  shoot  moves  in  the 
direction  of  free  space  and  air.  As  we  ascend  the  scale  of  the 
animal  kingdom,  we  find  numberless  creatures,  low  and  high, 
which  exhibit  such  a  choice  with  regard  to  surfaces.  The  stems 
of  polyps  grown  in  a  glass  tank  cling  closely  to  the  walls  of  the 
vessel,  but  their  upper  portions,  carrying  the  mouth  and  tentacles, 
turn  outwards  towards  the  open  space.  Free-swimming  larvae 
wriggle  out  of  a  crevice  if  they  drift  into  it.  Most  marine  worms 
move  about  restlessly  until  they  have  an  opportunity  of  burrowing 
into  sand,  or  of  creeping  into  some  chink  in  the  rocks.  A  very 
large  number  of  insects,  from  cockroaches  to  ants,  and  whether 
they  are  exposed  to  light  or  kept  in  the  dark,  will  move  about  rest- 
lessly until  they  can  squeeze  between  the  folds  of  a  sheet  of  paper, 
or  into  some  similar  place  where  they  are  in  contact  with  a  surface 
all  round.  In  an  aquarium,  pieces  of  drain-pipe  have  to  be  placed 
for  many  different  kinds  of  fish,  such  as  eels  and  pike,  whilst  others 
become  restless  if  they  are  enclosed  in  such  a  fashion.  So  also 
amongst  reptiles,  there  are  some  which  must  be  provided  with 
retreats  into  which  they  can  creep,  others  which  like  to  lie  in  the 
open.  Amongst  mammals  there  are  some  that  cannot  be  persuaded 
to  enter  any  box  or  chamber  if  it  appear  to  be  closed.  Deer, 
antelopes,  cattle  and  sheep  and  most  of  the  large  carnivores  can 
be  boxed  only  with  the  greatest  trouble,  sometimes  by  the  device 
of  making  the  box  apparently  a  narrow  tunnel  open  at  the  end 
turned  away  from  the  entrance.  Such  animals  often  damage 


234  CHILDHOOD  OF  ANIMALS 

themselves  seriously  in  their  endeavour  to  escape  from  a  closed 
chamber,  but  will  be  comparatively  content  if  at  least  one  of  the 
sides  is  protected  by  light  bars.  Another  set  of  mammals,  of  which 
the  small  rodents  are  the  best-known  instances,  at  once  enter  any 
little  hole  or  aperture  and  lie  placidly  in  a  closed  chamber.  In 
higher  animals  these  contact  reactions  naturally  are  modified  by 
other  factors,  such  as  positive  and  negative  phototropisms,  and 
they  are  affected  by  mental  factors,  but  none  the  less  they  are 
linked  up  with  the  simplest  responses  given  by  single-celled  organ- 
isms. Traces  of  them  survive  even  in  man.  In  nervous  subjects 
the  condition  of  claustrophobia  is  well  known.  Persons  affected 
by  it  have  an  almost  hysterical  dread  of  closed  spaces.  They  will 
hesitate  to  enter  a  very  small  room,  to  go  down  a  narrow  alley,  to 
sit  in  the  middle  of  a  row  at  the  theatre,  to  ride  in  a  closed  carriage. 
Victims  of  the  opposite  tendency  are  said  to  be  affected  with  agora- 
phobia. They  have  a  fear  of  open  spaces,  will  go  round  two  sides 
of  a  square  rather  than  cross  the  open  place,  are  happier  in  a  crowd, 
prefer  a  closed  carriage,  and  so  on. 

Chemotropisms,  or  attraction  to  or  repulsions  from  chemical 
stimulation,  occur  not  only  in  free-living  cells  but  in  the  separate 
cells  and  every  part  of  the  tissues  of  higher  animals  and  plants. 
Some  microbes  move  towards  a  supply  of  oxygen,  others  away  from 
it,  so  that  where  such  are  mixed  in  a  drop  of  water  under  the  micro- 
scope they  will  quickly  arrange  themselves  in  a  pattern,  one  set 
crowded  in  the  centre,  the  other  round  the  edges  where  the  water 
is  in  contact  with  the  air.  Weak  alcohol  repels  most  free-living 
cells,  weak  acid  attracts  them.  Some  will  move  towards  solutions 
of  sugar,  others  towards  meat- juice  diffusing  in  the  water.  One 
observer  found  that  when  he  had  a  number  of  ciliated  animalcula 
freely  swimming  in  a  drop  of  water  under  a  thin  slip  of  glass,  he 
could  kill  some  of  them  by  applying  a  hot  needle  to  the  surface  of 
the  glass  cover-slip.  The  motionless  bodies  soon  became  surrounded 
by  a  clear  space,  as  if  some  repelling  chemical  substance  had  exuded 
from  the  corpses,  and  he  applied  to  the  phenomenon  the  fanciful 
name  of  nekrophobia,  fear  of  the  dead.  The  meeting  of  the  sexual 
cells,  the  attraction  of  food,  the  senses  of  taste  and  of  smell  are  all 
cases  in  which  chemotropism  plays  an  important  part. 

I  have  given  only  a  few  simple  instances  of  these  fundamental 
reactions  of  living  matter.  They  occur  at  first  without  any  of  the 
complicated  bodily  machinery  through  which  they  act  in  the  higher 
forms  of  life.  They  are  not  rigid  like  the  actions  and  reactions 


THE  PURPOSE  OF  YOUTH  235 

between  bodies  of  matter  that  are  not  alive,  for  the  living  matter 
is  constantly  changing  and  almost  from  moment  to  moment  may 
behave  differently  with  regard  to  the  same  stimulus.  They  do 
not  occur  separately  and  independently,  but  in  all  the  higher  forms 
they  are  combined  in  varying  degrees.  But  without  doubt  they 
are,  so  to  say,  the  raw  materials  or  uncombined  elements  of  the 
instincts.  A  new-born  mammal  pressing  against  its  mother  and 
seeking  the  nipple  acts  through  a  complicated  nervous  and  muscular 
machinery  so  nicely  adapted  to  its  purpose  that  it  can  hardly  fail 
to  act.  But  it  acts  through  various  tropisms,  the  reactions  to 
warmth,  to  contact,  and  to  chemical  stimulation  through  taste 
and  smell. 

These  various  factors  of  instinct  can  be  modified  by  experience. 
In  a  few  cases  the  same  response  is  repeated  to  each  application  of 
the  stimulus,  but  it  is  far  more  usual  for  a  change  in  the  response 
to  take  place,  the  duration  of  the  change  increasing  in  the  higher 
animals  until  it  passes  into  what  can  be  called  memory.  An  in- 
fusorian  animalcule  will  go  on  bumping  up  against  an  obstacle 
indefinitely,  at  each  contact  recoiling,  twisting  over  and  charging 
again,  and  it  is  mere  luck  if  in  a  series  of  movements  of  this  kind 
it  finally  discovers  a  way  round.  A  worm  similarly  confronted 
with  an  obstacle  behaves  practically  in  the  same  way,  but  it  gets 
more  and  more  excited  in  its  movements,  and  may  finally  get  round 
by  some  violent  contortion,  more  or  less  in  the  fashion  that  a  man 
reading  a  book  will,  from  time  to  time,  simply  put  up  his  hand  to 
push  away  a  persistent  blue-bottle,  but  at  last  will  get  out  of  his 
chair  and  hunt  it  round  the  room.  In  the  latter  case,  however, 
in  addition  to  the  summation  of  the  irritating  effect  of  the  stimulus, 
the  higher  parts  of  the  man's  brain  come  into  play,  and  he  ceases 
to  be  merely  insti  ctive.  A  fish  which  was  kept  in  a  tank  was 
accustomed  to  come  to  a  particular  place  for  a  piece  of  food  that 
was  dropped  in.  Then  a  sheet  of  glass  was  fixed  between  the 
habitual  lurking-place  and  the  spot  where  the  food  was  dropped. 
For  some  time  the  fish  continued  to  dart  out  on  the  food,  bumped 
up  against  the  glass,  retired  and  returned  to  the  charge.  Presently, 
however,  it  ceased  to  respond,  and,  for  a  few  days  afterwards,  no 
longer  rushed  at  the  food  even  although  the  glass  had  been  removed. 
It  is  the  natural  instinct  of  a  spider  to  drop  from  its  web  at  any 
sudden  vibration,  or  when  a  shadow  is  thrown  on  it.  Mr.  and 
Mrs.  Peckham,  experimenting  with  spiders,  found  that  they  would 
drop  when  a  tuning-fork  was  sounded  near  them,  but  that  after 


236  CHILDHOOD  OF  ANIMALS 

fifteen  times  they  ceased  to  take  any  notice  of  the  disturbance. 
Even  extremely  simple  creatures  which  live  attached  to  a  surface 
by  a  contractile  stem  and  shrink  up  to  their  support  when  they  are 
touched  soon  fail  to  respond  to  a  repeated  stimulus.  The  infusorian 
Vorticella,  the  polyp  Hydra,  behave  in  this  way,  and  a  sea-anemone 
which  at  first  contracts  its  tentacles  when  they  are  touched  will 
very  quickly  cease  to  respond.  So  also  single-celled  creatures 
become  accustomed  to,  and  may  even  reverse  their  response  to 
weak  chemical  stimulation  ;  instead  of  withdrawing  from  alcohol, 
they  may  move  towards  it.  When  the  chemical  tropism  is  a  response 
to  a  food  substance,  it  may  cease  when  the  animal  is  satiated,  to 
be  resumed  later  on,  and  this  may  mean  no  more  than  a  change  of 
chemical  interaction  due  to  the  changed  condition  of  the  fully  fed 
organism.  When  a  sea-anemone  is  fed  a  certain  number  of  times 
in  succession  with  pieces  of  fish  or  flesh,  it  will  refuse  further  pieces, 
so  that  here  there  must  be  a  transference  to  the  tentacles  of  the 
change  produced  by  the  food  in  the  digestive  tract.  But  a  more 
complicated  change  in  reaction  has  also  been  obtained  by  experi- 
ments on  the  sea-anemone,  for  one  that  was  fed  repeatedly  on 
filter-paper  soaked  in  the  juice  of  a  crab  ejected  the  paper,  and 
after  some  experiments  would  not  even  swallow  it. 

There  is  no  doubt  but  that  the  effect  of  the  stimulus  can  be 
modified  or  reversed  by  repetition  in  all  the  simpler  cases  that  have 
been  tried.  These  results,  however,  wear  off  very  quickly  in  the 
case  of  single-celled  creatures  and  the  simpler  animals,  and  after 
a  lapse  of  time,  which  may  be  measured  in  minutes,  hours  or  days, 
the  normal  responses  to  the  stimulus  are  resumed.  We  may  sup- 
pose the  protoplasm  and  the  very  simple  mechanisms  of  muscle 
and  nerve  concerned  to  recover  from  the  fatigue  or  strain,  or 
abnormal  chemical  condition,  into  which  they  have  been  thrown, 
and  on  their  recovery  to  be  practically,  perhaps  completely,  un- 
altered. It  is  different,  however,  with  higher  animals,  where  there 
seems  to  be  a  power  of  registration  of  the  effects  of  experience,  a 
registration  that  becomes  not  only  more  complete  but  more  easily 
available  in  vertebrates  than  in  other  animals,  and  in  the  higher 
vertebrates  than  in  the  lower  vertebrates.  The  organic  mechanism 
itself  consists  of  a  simple  form  of  sensitive  organ  to  receive  the 
stimulation,  nerves  to  transmit  the  message  to  a  group  of  nerve- 
cells  which  again  directly  or  indirectly  control  a  group  of  muscles 
to  carry  out  the  reaction.  This  mechanism  may  be  permanently 
altered  by  experience,  but,  besides  such  alteration,  the  results  of 


THE  PURPOSE  OF  YOUTH  237 

experience  seem  to  be  stored,  so  to  say,  in  some  separate  receptacle. 
All  physiological  knowledge  points  to  part  of  the  grey  matter  on 
the  surface  of  the  brain  as  the  storehouse,  and  it  is  precisely  this 
region  which  becomes  relatively  larger  and  more  complex  in  the 
higher  vertebrates.  What  we  must  suppose  to  happen  in  those 
animals  which  possess  this  storehouse  of  experience  is  that  when 
stimulation  occurs  it  calls  up  or  awakens  not  only  the  special 
mechanisms  with  which  it  is  connected,  but  the  reservoir  of  past 
experience.  The  resulting  action  is  controlled  not  only  by  the 
mechanism,  but  by  the  effect  on  the  mechanism  of  the  stored  expe- 
rience. The  name  for  this  storehouse  of  experience  is  memory, 
so  that  what  happens  in  the  higher  animals  is  that  response  to 
;stimulus  is  increased,  controlled  or  modified  by  the  memory  of 
past  responses.  It  has  to  be  remembered  that  memory  need  not 
be  conscious.  Consciousness  is  the  most  difficult  idea  to  transfer 
from  ourselves  to  animals,  but  memory  we  can  observe  and  make 
the  subject  of  experiment.  Sometimes  the  word  memory  is  applied 
not  only  to  the  separate  storing  of  experience  in  the  reservoir  that 
we  must  believe  to  lie  in  the  grey  matter  of  the  brain,  but  to  the 
warping  of  the  actual  mechanism.  There  is  a  distinction  in  fact 
between  the  two.  We  can  see  the  more  sensitive  "  brain  memory  " 
switched  off  by  operation  or  disease,  or  by  drugs,  or  by  gusts  of 
passion  that  do  not  reach  the  mechanism.  And  we  see  by  keeping 
clear  the  distinction  between  the  two  the  opportunity  for  a  choice 
of  response  to  stimulation  ;  the  response  may  be  due  chiefly  to 
mechanism  or  chiefly  to  memory,  and  if  chiefly  to  memory,  to  one 
of  several  memories.  Add  consciousness  to  memory,  and  you 
will  find  it  very  difficult  to  distinguish  the  simultaneous  know- 
ledge of  several  different  possible  responses  from  what  we  know 
as  free  will. 

These  high  problems  have  taken  us  far  away  from  instinct. 
Although  what  I  believe  to  be  the  component  parts  of  the  instincts, 
the  responses  to  stimulation,  can  be  modified  by  experience,  the 
more  complicated  and  typical  instincts  are  not  modified  by  expe- 
rience, and,  indeed,  many  of  them  are  called  into  play  only  once 
in  the  life  of  an  individual.  Nature  has  chosen  another  path  for 
them.  They  have  been  built  up  in  the  long  history  of  the  race 
into  very  perfect  mechanisms  which  admit  of  no  alteration  and 
of  no  blundering.  Given  the  appropriate  conditions  and  the  result 
follows.  The  animals  are  fully  equipped  to  meet  a  certain  set  of 
circumstances,  and  if  these  present  themselves,  the  adaptation 


238  CHILDHOOD  OF  ANIMALS 

between  organism  and  environment  is  complete.  If  the  proper 
environment  does  not  present  itself,  the  instinct  cannot  come  into 
operation,  and  if  it  be  necessary  to  the  life  of  the  animal,  the  animal 
dies.  No  doubt  instincts  vary,  like  every  part  of  the  animal  organ- 
ism, and  in  course  of  time,  by  a  continuous  rejection  of  the  less 
suitable  variations  and  a  continuous  preference  of  the  more  suitable 
variations,  an  instinct  might  change.  But  so  far  as  the  individual 
is  concerned,  the  instinct  is  fixed. 

The  operation  of  an  instinct  requires,  in  proportion  to  its  com- 
plexity, a  certain  complexity  of  structure,  and  unti  the  latter  has 
been  attained  it  cannot  take  place.  On  the  other  hand,  it  does 
not  require  practice,  and  there  is  no  reason  why  animals  that  rely 
upon  instincts  should  have  their  period  of  youth  longer  than  the 
time  required  for  bodily  growth  and  development.  In  the  verte- 
brates, however,  and  especially  and  increasingly  so  in  vertebrates 
with  high  brain  development,  the  rigid  instincts  are  being  broken 
down  and  replaced  by  actions  controlled  by  experience  and  by 
memory,  and  so  fitting  more  varied  circumstances  and  more  varied 
environment.  The  period  of  youth  is  prolonged  to  afford  time  for 
this.  The  animals  are  protected  and  cared  for  by  their  parents, 
and  allowed  a  space  in  which  the  burden  of  life  does  not  press 
heavily  upon  them,  and  in  this  time  they  have  to  educate  their 
instincts,  destroy  their  rigidity,  allow  them  to  be  controlled  by  the 
stored-up  results  of  experiment.  The  purpose  of  youth  is  to  give 
time  for  this,  and  therefore  those  animals  which  are  most  intelligent, 
which  have  the  most  complex  brains,  have  the  longest  period  of 
youth. 


CHAPTER  XV 
EDUCATION 

THERE  is  no  complete  separation  between  instinct  and  experimental 
action.  The  animals  in  which  instinct  rules  come  into  their  full 
powers  at  once,  and  have  little  or  nothing  to  gain  from  experience. 
But  the  higher  types  of  animals,  those  in  which  experimental  action 
directed  from  the  experience  stored  in  the  brain  is  the  dominating 
feature  of  life,  start  with  certain  clearly  marked  aptitudes  or  ten- 
dencies which  may  be  called  instinctive.  It  is  not  merely  because 
a  carnivore  has  teeth  and  claws  that  it  becomes  a  beast-of-prey,  or 
because  a  duck  has  webbed  feet  that  it  begins  to  swim.  In  the 
slow  process  of  evolution,  the  structure  of  different  kinds  of  mammals 
has  become  so  fitted  to  the  kind  of  life  they  are  going  to  lead  that 
it  is  difficult  for  their  machinery  to  work,  so  to  speak,  in  any  way 
but  the  way  for  which  it  is  fitted.  And  part  of  the  structure  is 
the  unconscious  nervous  mechanism  which  lies  behind  instinct, 
and  which  requires  time  for  growth,  but  not  necessarily  time  for 
training.  But  however  definite  may  be  the  direction  of  apti- 
tudes, most  of  these  have  to  be  educated  by  experiment  and  teach- 
ing, to  adapt  them  to  the  varying  circumstances  to  which  they 
must  be  applied.  The  animals  have  to  be  initiated  into  life,  they 
have  to  learn  to  use  their  bodies.  The  moment  a  may-fly  has  freed 
itself  from  its  pupal  case,  it  is  able  to  crawl  up  on  a  dry  bank,  and 
the  moment  its  wings  have  expanded  under  the  influence  of  light 
and  air,  it  flies  off  with  as  complete  control  of  its  powers  as  it  will 
ever  have  during  its  short  life.  This  is  not  so  with  most  of  the 
powers  of  the  higher  animals.  They  have  to  learn  control  over 
their  own  body  and  over  their  special  kind  of  locomotion.  Even 
when  they  are  strong  and  active,  young  birds  and  mammals  fly 
or  run  against  obstacles,  lose  their  balance,  fail  to  stop  in  time  or 
to  turn  quickly,  and  hurt  themselves  in  many  ways.  The  very  flexi- 
bility of  their  powers  makes  it  more  difficult  to  exercise  them  with- 
out practice.  They  have  to  acquire  skill  in  obtaining  their  food,  as 
well  as  knowledge  of  what  that  food  is.  To  nibble  grass,  to  gnaw 

239 


240  CHILDHOOD  OF  ANIMALS 

roots,  to  strip  fruit  or  leaves  from  trees  require  a  certain  amount 
of  skill,  and  it  is  amusing  \  o  see  how  clumsily  young  animals  usually 
set  about  these  necessary  tasks.  When  the  food  is  a  living  prey 
that  runs  or  jumps  or  turns  on  its  enemy,  even  greater  knowledge, 
skill  and  agility  are  required.  The  young  animals  have  to  learn 
to  defend  themselves  by  recognising  danger,  by  hiding  or  escaping 
by  swiftness,  or  by  fighting. 

Young  birds  and  mammals  differ  very  much  in  the  difficulty 
they  seem  to  have  in  acquiring  their  various  forms  of  locomotion. 
Ducklings,  even  if  they  have  been  reared  under  a  hen,  take  to  the 
water  at  once  and  swim  without  any  practice.  Cygnets  have  to 
be  coaxed  or  pushed  into  the  water  by  their  parents,  and  seem 
anxious  to  get  out  of  it,  either  on  the  bank  or  by  climbing 
on  the  backs  of  the  adults  (see  Plate  XI).  Young  gulls 
avoid  the  water  for  a  considerable  time,  but  eventually  are 
taken  to  it  by  their  parents.  The  aquatic  mammals,  except, 
of  course,  whales,  dolphins  and  porpoises,  manatees  and 
dugongs,  are  all  born  on  land,  and  have  to  be  coaxed  or  driven 
into  the  water  by  their  parents,  but  as  soon  as  they  get  there 
swim  as  instinctively  as  fishes  or  snakes.  So  far  as  I  know, 
all  the  quadrupeds  are  able  to  swim,  partly  because  the  attitude 
in  the  water  and  the  movements  of  the  limbs  are  not  very  different 
from  those  to  which  they  are  accustomed.  Most  of  them  are  very 
much  alarmed  at  first  and  would  readily  drown  from  the  exhaustion 
produced  by  their  violent,  spasmodic  efforts.  The  fact,  however, 
that  most  of  them  soon  become  accustomed  to  water,  and  swim  with 
ease  for  long  distances,  shows  the  remarkable  difference  between 
their  flexible  varied  possibilities  and  the  rigid  adaptation  of  lower 
animals. 

The  ancestors  of  birds  were  quadrupeds  and  no  doubt  walked 
on  all  fours  like  most  living  lizards.  The  front  limbs  have  been 
transformed  into  wings,  and  birds  are  now  purely  bipeds,  walking, 
hopping  or  running  only  on  their  hind-legs.  This  form  of  loco- 
motion appears  to  be  more  difficult  to  learn  than  the  quadrupedal 
gait  of  four-legged  creatures.  Newly  hatched  chicks  take  some 
hours  to  learn  to  walk,  even  if  they  are  helped  by  the  mother.  At 
first  they  shuffle  along  clumsily,  using  the  wings  as  crutches.  The 
wing  of  a  nestling  chick  has  a  little  claw  at  the  tip  of  the  thumb, 
and  if  a  still  earlier  stage  be  examined,  the  tips  of  the  first  and 
second  fingers  as  well  as  the  thumb  are  seen  to  be  separate,  and 
appear  as  if  they  were  going  to  develop  claws,  although  they  do 


BLACK-NECKED  SWAN  CARRYING 
CYGNETS  ON  HER  BACK 


nount 

Uimsily  young  animals  usually 
hen  the  food  is  a  living  p 
reater  knowlecL 
nimals  have  to  let 
by  hiding  c 

ry  much  in  the  difBcv: 
forms  of  locomoti 
ler  a  hen,  take  to  the 
Cygnets  have  to 
Barents,  and  seem 
or  by  climbing 

Young    gi- 
but    eventually  are 
'iiammals,    except, 
manatees     and 

or  dri 

->44aget  t3 

Sim  Vs.  O,*  as  I  kn 

.se  the  attitude 
not  very  differ 
-t  of  them  are  v- 
drown  from  the  exhaust 
The  fact,  howt- 
d  to  water,  and  swim 
arkable  difference  betv 
id  adaptation  of  lo 

and  no  doubt  wa, 
The  front  limbs  have  b 
ow  purely  bipeds,  walk 
This  form  of  1 
i  than  the  quadrui 
hatched  chicks  ta! 
by  the  / 
;s  as  cm 

at  the  tip  of  the  thumb, 
i,  the  tips  of  the  first 
en  to  be  separ 
laws,  although  the} 


I 


"•"f1 


f 


EDUCATION  241 

not  actually  do  so.  The  nestlings  of  the  common  moorhen,  of  the 
porphyries,  and  of  quite  a  number  of  birds  that  haunt  reeds  and 
water-weeds  have  a  well-developed  claw  on  the  thumb,  and  by 
the  help  of  this,  use  the  wing  in  scrambling  over  the  nest.  The 
nestling  of  a  peculiar  South  American  bird,  the  hoatzin  or  stink- 
pheasant,  has  not  only  a  thumb-claw  but  a  claw  on  the  index  finger. 
The  nests  are  built  high  up  in  trees  overhanging  the  water,  and 
for  some  time  the  little  birds  crawl  over  the  twigs  on  all  fours  like 
young  reptiles.  It  is  clear  that  the  bipedal  gait  is  a  recent  acquisi- 
tion, and  traces  of  the  older  form  of  walking  are  seen  not  only  in 
the  structure  of  young  birds,  but  in  the  difficulty  which  they  have 
in  learning  to  walk. 

Little  quadrupeds  find  it  easy  to  walk  as  soon  as  their  legs  are 
strong  enough  to  support  them.  Young  kangaroos,  when  they 
begin  to  come  out  of  the  pouch,  use  their  front  paws  a  great  deal 
in  walking,  and  only  gradually  acquire  the  hopping  gait  of  the 
adult.  Most  monkeys  are  really  quadrupeds  in  gait,  and  when 
they  are  running  fast  on  the  ground,  gallop  on  all  fours.  Little 
monkeys  certainly  do  so,  and  it  is  only  when  they  jump  up  on  their 
mother  or  on  a  branch  that  they  use  their  hands  as  hands  rather 
than  as  paws.  Even  when  they  are  climbing  trees,  the  posture 
of  monkeys  is  not  upright,  and  all  the  young  chimpanzees  and 
orangs  that  I  have  seen  get  on  all  fours  when  they  are  moving 
quickly.  Gibbons  run  on  their  hind-legs,  with  their  bodies 
erect,  but  with  an  uneasy  swaying  movement,  using  their  long 
arms  as  balancers  and  holding  them  ready  to  give  support  at  any 
moment.  Human  children,  of  course,  begin  to  crawl  on  all  fours 
and  learn  to  walk  only  with  much  difficulty  and  with  a  good  deal 
of  persuasion  and  help. 

The  difficulty  which  bipeds  have  in  learning  to  walk  is  thus  due 
to  a  double  cause.  In  the  first  place  the  action,  like  most  of  the 
actions  of  the  higher  animals,  is  not  purely  an  instinct,  but  the 
complex  balancings  and  the  varied  movements  are  learned  partly 
by  experience.  In  the  next  place,  it  is  a  comparatively  recent 
acquisition  of  the  race,  and  the  structure  still  contains  many 
elements  which  are  not  yet  completely  adapted  to  it. 

Learning  to  fly  is  a  still  more  difficult  task.  Young  swallows 
are  said  to  fly  without  any  teaching  or  persuasion,  and  it  may  be 
that  these,  which  are,  perhaps,  the  most  completely  aerial  of  birds, 
have  reached  a  stage  which  most  birds  are  only  on  the  way  to 
reach.  In  most  cases,  the  mothers  have  to  use  persuasion  or  force, 
C.A.  Q 


242  CHILDHOOD  OF  ANIMALS 

and  to  protect  the  fledglings  from  hurting  themselves  in  their  first 
efforts.  Sparrows  may  be  seen  tempting  their  young  into  the  air 
by  offering  them  food  and  then  flying  off  a  little  distance  before 
it  has  been  taken.  The  mother  stork  pushes  the  young  birds  off 
the  edge  of  the  nest  or  chimney-stack  on  which  they  have  been 
resting.  Most  of  the  birds-of-prey  and  many  of  the  perching  and 
singing  birds  push  their  young  off  a  support  and  then  hurriedly 
fly  under  them  to  break  their  fall.  Even  after  the  first  fluttering 
movements  have  been  made,  young  birds  take  weeks  or  months 
before  they  acquire  perfect  control,  before  they  can  turn  in  the  air 
alight  suddenly  on  a  branch  or  even  on  the  ground,  and  certainly 
before  they  can  readily  launch  themselves  into  the  air  from  the 
ground.  I  have  not  been  able  to  obtain  any  information  as  to 
how  young  bats,  flying  squirrels  and  other  volant  mammals  take 
to  the  air.  I  should  expect  to  find  that  they  learn  with  difficulty 
and  that  they  are  aided  by  their  parents. 

The  process  of  learning  to  eat  shows  an  intimate  blending  of 
instinct  and  experience  in  both  birds  and  mammals.  The  instinctive 
part  resides  chiefly  in  the  senses  of  taste  and  smell,  and  the  part 
that  comes  by  experience  is  the  association  of  appearance  with 
edible  qualities.  But  the  matter  is  further  complicated  by  the 
fact  that  many  young  birds  and  mammals  are  fed  by  their  parents 
and  would  otherwise  starve  in  the  midst  of  plenty.  In  the  case 
of  birds,  those  that  are  hatched  in  an  active  condition  generally 
pick  up  their  own  food  almost  at  once.  At  first  they  peck  at  every- 
thing, taking  stones,  grains,  fragments  of  vegetation,  insects  or 
pieces  of  flesh,  but  very  soon  select  only  vegetable  matter  if  they 
are  eaters  of  plants,  different  kinds  of  material  if  they  are  omni- 
vorous, or  grubs,  insects,  fish  or  flesh  if  they  are  carnivorous.  The 
carnivorous  young  birds  do  not  seem  to  have  any  strongly  marked 
choice  between  fish  and  flesh.  A  good  many  of  the  active  young 
birds  are  assisted  by  their  parents,  either  by  food  being  brought 
to  them,  or  disgorged  in  front  of  them,  and  these  when  they  are 
left  to  themselves  will  pick  up  food,  but  will  die  rather  than  hunt 
for  it.  They  learn  only  slowly  that  food  may  be  edible  even  although 
it  is  not  brought  by  the  parent.  All  the  birds  in  the  mouths  of 
which  the  parents  place  the  food  take  a  very  long  time  to  associate 
the  appearance  of  food  with  the  idea  of  eating.  If  substances  are 
actually  placed  in  their  mouths,  they  instinctively  swallow  them, 
but  reject  them  if  they  are  unsuitable,  and  soon  learn  to  do  so 
without  having  swallowed  them.  On  the  other  hand,  hungry  young 


EDUCATION  243 

birds,  large  enough  to  be  able  to  hop  on  the  branches  or  even  on 
the  ground,  will  shriek  for  food  with  their  bills  gaping  widely, 
although  attractive  worms  are  wriggling  and  squirming  within  an 
inch  of  their  nose  and  eyes.  When  they  are  rather  older  and  have 
learned  to  go  in  quest  of  their  food,  they  are  still  indiscriminate. 
Opinions  are  divided  as  to  how  far  old  and  experienced  birds  eat 
the  brightly  coloured,  nasty-tasting  caterpillars  and  insects  which 
are  supposed  to  warn  prospective  enemies  of  their  unpalatableness 
by  their  gaudy  hues,  but  it  is  at  least  certain  that  young  birds  have 
no  instinctive  knowledge  of  this  kind  of  advertisement,  and  greedily 
eat  creatures  with  which  their  palates  or  their  stomachs  quarrel. 

There  is  much  the  same  set  of  differences  amongst  young  mam- 
mals. The  act  of  suckling  seems  to  be  purely  instinctive  and  takes 
place  as  soon  as  the  little  creature  finds  the  warm  nipple.  An 
artificial  teat  arouses  the  instinctive  action  nearly  as  well  as  the 
natural  organ,  and  young  mammals  take  readily  to  the  bottle. 
But  if  the  liquid  supplied  be  cold,  or  very  different  in  flavour  from 
milk,  the  reflexes  do  not  work  and  the  material  is  not  swallowed. 
When  the  milk  diet  begins  to  be  varied  with  other  substances,  there 
is  an  interplay  of  instinct  with  the  results  gained  by  experiment. 
The  vegetarians  will  not  attempt  to  nibble  flesh  or  fish  or  living 
animals,  but  they  take  some  time  to  learn  the  difference  between 
grass  and  dry  paper,  and  so  forth.  The  sense  of  smell  and  that  of 
taste  are  certainly  present,  but  act  at  first  only  on  acute  differences 
and  lead  them  to  reject  certain  substances  rather  than  to  show 
preferences  amongst  those  that  they  will  take.  When  they 
are  a  little  older,  they  begin  to  select,  but  the  choice  they  make  is 
difficult  to  understand.  I  have  offered  green  vegetation  of  different 
kinds  to  many  young  herbivorous  mammals  with  most  conflicting 
results.  They  are  attracted  by  green  colour,  and  I  have  never 
found  any  that  would  refuse  such  palatable  and  wholesome  leaves 
as  willow,  poplar,  hawthorn  and  elm.  Young  camels,  sheep,  goats 
and  deer  will  take  leaves  like  elder  into  their  mouths,  and  some  of 
them  will  swallow  it,  whilst  others  reject  it  after  having  tasted  it. 
Antelopes  and  cattle  are  more  wary  or  have  a  keener  sense  of  smell, 
for  they  generally  refuse  leaves  of  elder  after  smelling  them 
but  before  tasting  them.  Green  French  beans,  of  which  most 
young  animals  can  have  no  experience,  are  approached  with  the 
greatest  caution  and  are  generally  refused  until  a  good  deal  of 
persuasion  has  been  employed,  although  I  cannot  perceive  that 
these  vegetables  have  any  appreciable  odour.  When  animals  have 


244  CHILDHOOD  OF  ANIMALS 

taken  them  once,  and  chewed  and  swallowed  them,  they  recognise 
them  again  and  seize  them  greedily.  Green  onions,  celery  and 
some  other  wholesome  but  strong-smelling  leaves  most  of  the 
animals  to  which  I  have  offered  them  have  taken  at  once.  I  do 
not  think  that  there  is  any  instinctive  recognition  of  or  rejection  of 
poisonous  plants  ;  the  young  animals  have  good  memories,  and  if 
a  plant  is  unpleasant  either  to  the  sense  of  smell  or  still  more  to  the 
palate,  it  is  rejected  after  trial  and  not  taken  again. 

Young  mammals  which  naturally  would  have  their  food  brought 
to  them  by  their  parents,  seem  to  have  a  very  small  amount  of 
instinctive  selection  or  rejection,  and  when  they  are  brought  up 
by  hand  will  take  very  unsuitable  food.  This  at  least  has  the 
convenience  that  they  are  not  at  all  difficult  to  get  to  feed  when 
they  are  being  brought  up  artificially,  and  will  often  live  for  a  time 
on  very  erroneous  diet.  Many  of  them  that  have  been  treated  in  this 
way  acquire  unwholesome  tastes  which  are  not  easy  to  replace. 
Young  walruses  and  polar  bears  have  reached  zoological  collections 
after  having  been  kept  alive  since  their  capture  on  whales'  blubber, 
which  is  certainly  an  unsatisfactory  diet  for  a  growing  animal,  and 
there  has  been  the  greatest  difficulty  in  getting  them  to  take  fish 
or  flesh. 

Thus  even  in  the  simplest  and  most  necessary  parts  of  their 
activities,  young  birds  and  mammals  do  not  spring  fully  equipped 
into  life,  but  have  to  learn  by  trying.  They  have  instincts,  but 
these  carry  them  only  a  little  way.  Few  of  them  can  walk  or  swim 
or  fly  without  laborious  practice,  often  aided  by  help  or  coercion 
from  their  parents.  They  have  not  full  control  even  over  their 
muscular  powers,  and  there  is  not  a  proper  adjustment  of  the  co- 
ordination between  eyesight  and  movement.  They  overbalance 
themselves,  totter,  outrun  themselves,  stumble  and  bump  about, 
miscalculating  distances,  and  are  blundering  creatures  in  an  un- 
familiar world,  whilst  the  lower  animals  take  up  the  game  of  life 
as  if  they  were  only  renewing  it  after  a  sleep.  At  first  sight,  the 
advantage  seems  to  rest  with  the  animals  guided  and  ruled  by 
perfected  instincts,  but  we  have  to  remember  that  they  are  at  the 
mercy  of  the  chance  of  finding  the  right  conditions  and  the  right 
stimulations  to  awaken  these  instincts.  If  the  conditions  are  wrong, 
the  world  is  not  merely  strange,  but  forbidding,  hostile,  impossible, 
and  they  perish.  The  higher  types,  being  less  accurately  adjusted 
to  any  particular  environment,  can  become  accustomed  to  a  much 
wider  range  of  environment.  No  conditions  are  quite  right  for 


EDUCATION  245 

them,  but  they  can  learn  to  make  shift  with  almost  any  conditions 
in  which  they  happen  to  find  themselves.  It  is  with  this  task  of 
fitting  themselves  to  the  world  that  they  occupy  their  youth,  and 
it  is  for  this  task  that  they  enjoy  a  prolonged  period  of  youth  and 
a  degree  of  freedom  from  the  immediate  cares  of  finding  their  own 
livelihood  and  protecting  themselves  against  the  dangers  of  the 
world. 

The  high  spirits  of  young  animals  are  proverbial.  The  Latin 
song,  familiar  to  university  students  of  the  Calvinistic  North, 
"  Gaudeamus  igitur,  juvenes  dum  sumus  " — "  Let  us  rejoice  whilst 
we  are  still  young ' ' — is  at  once  needlessly  defiant  and  needlessly  apolo- 
getic. The  random  high  spirits  of  youth  are  as  necessary  and  inevitable 
as  the  serious  and  restrained  pertinacity  of  maturity.  Not  only  young 
human  beings,  but  young  apes  and  monkeys,  carnivores  and  herbi- 
vores, rodents  and  edentates,  liberate  an  excess  of  vitality  in  the 
wildest  antics.  But  it  is  to  be  noticed  that  this  is  not  true  of  all 
young  animals.  Caterpillars  young  cockroaches  or  grasshoppers, 
lobster,  or  crabs  or  snails  are  not  to  be  distinguished  from  their 
seniors  by  any  excessive  gaiety.  The  exuberance  of  youth  begins 
with  the  higher  animals  and  increases  as  we  ascend  the  scale  of 
vertebrate  life,  precisely  as  parental  care,  intelligence  and  relative 
duration  of  youth  increase.  The  high  spirits  of  youth  are  part  of 
the  new  order  of  things  in  which  the  period  of  youth  is  devoted 
to  the  replacement  of  instinctive  action  by  experimental  action. 

It  used  to  be  said  that  as  young  animals  of  these  higher  types 
were  fed  and  protected,  they  had  a  surplus  of  income  over  output, 
and  that  their  high  spirits,  expressed  in  games  and  antics,  were 
the  inevitable  result  of  this  surplus  vitality.  Certainly,  if  they 
were  left  to  themselves,  they  might  have  no  spare  energy,  but  to 
say  that  their  exuberance  is  the  mere  discharge  of  a  waste  product 
is  to  read  very  plain  facts  wrongly.  They  are  fed  and  protected 
in  order  that  they  may  have  surplus  energy,  and  they  require  the 
surplus  energy  for  the  experimental  business  of  their  youth.  They 
use  their  surplus  energy  in  ceaseless  experiment  with  all  their  powers. 
Limbs,  claws,  nose,  teeth,  tail,  all  their  senses  and  organs  are 
exercised  in  every  possible  way,  are  applied  in  every  possible  direc- 
tion, on  e  ery thing  that  comes  within  their  reach.  They  learn  to 
use  their  natural  powers,  they  gain  experience  of  their  limitations, 
and  acquire  knowledge  of  the  world. 

The  destructive  habits  of  young  animals  are  by  no  means  specially 
marked  in  predaceous  creatures,  but  are  simply  a  part  of  the  experi- 


246  CHILDHOOD  OF  ANIMALS 

mental  curiosity  of  youth.  Human  children,  until  they  have  been 
laboriously  taught  to  behave  differently,  pull  to  pieces  everything 
they  can  get  hold  of,  toys,  dolls,  implements  of  all  kinds,  and  even 
such  live  animals  as  they  are  able  to  reach,  using  their  teeth  and 
fingers  in  the  work  of  destructive  exploration.  Young  monkeys 
behave  exactly  in  the  same  way.  They  break  all  the  toys  that 
are  given  to  them,  tear  their  blankets,  pick  their  bedding  to  pieces 
and  scatter  it  about,  spend  almost  inexhaustible  patience  in  un- 
ravelling the  wire  of  their  cages,  or  in  trying  to  open  the  doors  or 
break  the  hinges,  and,  just  like  children,  they  can  be  taught,  up 
to  a  certain  point,  to  handle  things  more  carefully  and  to  refrain 
from  breaking  them  in  the  presence  of  their  keepers.  But  as  soon 
as  they  are  left  alone,  they  resume  their  occupation.  Puppies, 
the  cubs  of  wolves  and  foxes,  and  kittens  of  every  kind,  colts,  the 
fawns  of  deer  and  antelopes,  calves  and  kids,  and  even  young 
elephants  show  the  same  restless  exploring  energy.  There  is  no 
corner  of  my  study  that  my  young  hyrax  has  not  thoroughly  in- 
vestigated, pulling  books  out  of  their  shelves,  nibbling  the  corners 
of  papers,  pulling  about  the  skins  of  birds,  trying  teeth  on  the  tele- 
phone receiver  and  the  electric  lamp-shades,  jumping  up  against  and 
trying  to  push  over  things  out  of  reach.  It  has  now  learned  to  stop 
when  I  shout  "No "  across  the  room,  but  at  once  proceeds  to  hunt 
for  a  new  game.  Its  greatest  delight  is  to  climb  on  my  shoulder 
and  tug  at  my  tie  until  it  has  succeeded  in  unfastening  it.  Some 
birds,  such  as  parrots  and  cockatoos,  remain  mischievous  and 
destructive  all  their  lives  and  beguile  the  tedium  of  captivity  by 
pecking  and  gnawing  every  object  they  are  able  to  damage,  and 
sheet  iron  seems  the  only  material  that  beats  them  ;  they  destroy 
the  woodwork  of  their  cages,  twist  and  unpick  the  wire,  strip  the 
bark  from  every  piece  of  wood,  root  up  every  plant,  and  pull 
to  pieces  and  scatter  any  faggots  that  are  placed  to  shelter  them. 
But  most  birds  in  their  youth  have  similar  instincts,  and  often 
cause  their  parents  much  labour  in  repairing  the  damage  they  do 
to  the  nest. 

Much  of  the  experimental  activity  of  the  young,  and  especially 
that  shown  in  games,  is  not  random,  but  is  denned  and  directed  by 
their  structure  and  instincts.  Professor  Groos  has  shown  that  the 
games  of  young  animals  bear  a  definite  relation  to  their  future  life  ; 
he  has  extended  to  other  mammals  the  application  of  the  saying 
that  the  battle  of  Waterloo  was  won  on  the  playing  fields  of  Eton. 
Animals  that  have  to  escape  or  to  catch  their  prey  by  swiftness 


EDUCATION  247 

'and  dexterity  rush  madly  in  circles,  or  race  each  other  until  they 
have  to  lie  down  from  exhaustion.  Goats,  sheep  and  chamois  are 
mountainous,  rock-loving  animals,  accustomed  to  make  high  vertical 
jumps  from  one  ledge  to  another.  Their  kids  and  lambs  practise 
high  jumps  with  an  effect  that  is  ludicrous  when  we  see  them  on 
flat  ground  suddenly  springing  into  the  air.  Rocky-mountain 
,goats  are  said  to  be  the  most  sure-footed  of  all  animals  ;  they 
are  slow  and  deliberate  in  their  movements,  creeping  along  almost 
invisible  ledges  on  the  face  of  precipitous  cliffs.  Their  kids  show 
the  same  stealthy  and  careful  movement,  climbing  to  the  roof  of 
their  shelter,  not  by  sudden  jumps,  but  almost  inch  by  inch.  Gazelles 
and  antelopes  which  inhabit  open  plains  practise  long  jumps  when 
they  are  young.  Young  dogs  and  wolves  run  round  and  round  in 
circles  trying  to  head  each  other  off.  Most  of  the  smaller  cats  are 
accustomed  to  take  almost  vertical  high  jumps ;  domestic  kittens 
can  be  seen  to  make  sudden  leaps  in  the  air  almost  like  young  goats  ; 
my  tame  caracal  kitten  used  to  stop  suddenly  when  running,  gather 
its  legs  together  and  make  most  comical  vertical  leaps  in  the  air. 
Caracals  in  the  wild  state  prey  chiefly  on  birds,  which  they  stalk 
until  they  flush  them,  and  then  leap  in  the  air  and  catch  them  on 
the  wing.  I  have  seen  an  adult  caracal  in  the  Zoological  Gardens 
stand  under  a  shelf  five  feet  above  him,  look  up  at  it  as  if  measuring 
it  with  his  eye,  and  then  reach  it  by  a  straight  vertical  jump  without 
a  run.  Climbing  animals,  when  they  are  young,  practise  climbing 
assiduously.  My  tame  hyrax,  almost  day  by  day,  found  some  new 
feat  to  attempt,  and  kept  trying  until  it  succeeded.  One  of  its 
first  serious  experiments  was  to  climb  the  smooth  leg  of  an  iron 
bedstead,  which  it  did  at  first  rather  clumsily,  choosing  after 
many  vain  efforts  the  leg  that  stood  in  a  corner,  and  getting 
up  by  pressing  its  back  against  the  angle, of  the  wall  and  its  feet 
against  the  iron  rod,  much  in  the  fashion  that  a  mountain  climber 
ascends  a  "chimney."  It  soon  became  perfect  in  this  method  of 
reaching  the  bed,  and  then  proceeded  to  acquire  the  art  of  swarming 
up  the  more  difficult  legs  where  there  was  no  wall  to  help.  The 
smooth  leg  of  a  mahogany  chair  was  then  mastered.  The  polished 
rails  of  a  hot-water  towel  stand  took  a  longer  time,  but  the  little 
animal  persevered  until  it  had  learned  to  climb  the  vertical  bars 
and  walk  along  each  of  the  horizontal  bars,  and  finally  to  swing 
down  from  one  horizontal  bar  to  another.  One  evening  it  dis- 
covered that  it  was  possible  to  ascend  the  vertical  moulding  that 
surrounded  a  door.  The  moulding  was  about  four  inches  across 


248  CHILDHOOD  OF  ANIMALS 

and  projected  an  inch  and  a  half  from  the  wall.  The  hyrax  straddled 
this,  pressing  against  the  projecting  edges  with  the  palms  of  its 
fore-paws  and  the  soles  of  its  feet,  and  got  a  good  way  up  in  a  series 
of  little  jumps.  Its  usual  method  of  descending  a  pipe  was  to 
turn  round  and  come  down  head  foremost,  which  was  impossible 
in  this  case.  It  suddenly  stopped  and  shrieked  until  I  came  and 
helped  it  down.  It  then  at  once  made  a  second  attempt,  I  standing 
near  ;  when  it  got  near  the  top,  it  turned  round  as  if  to  see  that 
help  was  at  hand,  and  then  slowly  slid  down  backwards,  refusing 
any  assistance.  When  it  found  that  it  was  possible  to  get  down 
safely,  it  tried  again  and  again,  until  at  the  fifth  attempt  it  reached 
the  top  of  the  door,  where  it  could  turn  round  and  come  down  in 
the  way  it  preferred.  A  lesson  once  acquired  was  never  forgotten  ; 
after  finding  out  how  to  master  a  difficulty,  the  animal  never  bungled. 
Similar  observations  have  been  made  on  many  young  animals, 
but  particularly  in  domestic  animals.  In  the  case  of  the  hyrax 
there  was  no  possible  taint  of  ancestral  modification  by  domestica- 
tion, as  its  ancestors  from  time  immemorial  had  lived  in  the  high 
tree-tops  of  Nigeria.  I  have  said  a  good  deal  about  it  not  merely 
because  it  was  an  engaging  and  unfamiliar  pet,  belonging  to  a  group 
of  mammals  of  which  we  do  not  know  much,  but  because  it  shows 
admirably  the  fundamental  difference  between  the  instinctive  and 
the  experimental  types  of  action,  and  the  great  advantage  that 
those  animals  enjoy  which  have  the  power  of  fitting  their  natural 
capacities  to  any  strange  environment  in  which  they  may  come  to 
be  placed. 

The  games  of  young  carnivores  have  a  direct  bearing  on  the 
catching  of  a  living  prey.  A  kitten's  play  with  a  reel,  patting  it, 
making  it  roll  to  a  distance  and  then  springing  on  it,  like  the  game 
of  the  mother  with  a  real  mouse,  is  a  method  of  training  the  eye 
and  muscles  for  the  important  business  of  catching  dinner.  The 
natural  instinct  for  such  games  is  inborn,  but  the  capacities  have 
to  be  trained.  The  mother  of  wild  carnivores  gives  her  kittens 
or  cubs  the  tip  of  her  tail  as  a  toy,  making  it  quiver  to  attract  their 
attention,  flicking  it  away  from  them  and  tempting  them  to  spring 
on  it.  My  caracal  kitten,  which  had  been  removed  from  its  mother 
long  before  it  was  old  enough  to  play,  amused  itself  with  a  reel  and 
a  ball  exactly  like  a  domestic  kitten.  When  it  was  being  played 
with,  it  used  to  bring  back  the  ball  and  lay  it  down  to  be  thrown, 
but  it  invented  a  game  of  its  own.  There  is  a  rather  long  corridor 
in  my  house  where  it  was  possible  to  have  a  very  good  game  of  ball. 


EDUCATION  249 

At  first  the  caracal  used  to  bring  the  ball  back  to  one  end  of  the 
corridor  and  chased  it  as  soon  as  it  was  rolled  along,  in  a  few  days 
learning  not  to  dash  up  against  the  wall  at  the  end,  if  it  had  not 
previously  captured  the  elusive  prey.  But  it  tired  of  this,  and, 
having  brought  back  the  ball,  it  would  dash  half-way  down  and 
lurk  in  one  of  the  doorways  where  it  could  not  see  the  ball  except 
for  the  moment  it  flashed  by,  and  the  game  was  not  to  run  after 
it,  but  to  intercept  it  as  it  passed. 

Many  of  the  games  of  young  animals  are  preparations  for  fighting. 
Kids,  lambs  and  calves  butt  and  engage  in  endless  mimic  combats. 
Deer  stand  up  on  their  hind-legs  and  fight  with  their  fore-legs. 
Young  donkeys,  horses  and  zebras  dash  at  one  another,  rearing 
and  striking  with  their  heads  and  fore-legs.  All  the  young  carni- 
vores romp  and  tussle  with  each  other.  Puppies  try  to  seize  their 
friendly  enemy  by  the  throat,  to  roll  it  over  and  to  hold  it  down  ; 
the  vanquished  animal  lies  on  its  back  and  strikes  ou  twith  its  fore- 
paws.  Young  lions,  tigers,  cats  of  all  kinds  and  young  bears 
wrestle  and  struggle  with  each  other,  sometimes  biting  rather 
severely.  My  caracal  was  extremely  fond  of  fighting  in  a  playful 
way.  He  used  to  bring  to  me  a  felt  slipper  and  invite  me  to  take 
it  from  him,  when  a  wild  romp  with  teeth  and  paws  followed ;  he 
tried  hard  to  remember  not  to  bite  me,  but  in  the  excitement  of 
the  struggle  sometimes  forgot  or  misjudged.  His  favourite  attitude 
of  defence  was  to  lie  on  his  back,  holding  the  slipper  in  his  teeth, 
and  ready  to  strike  out  with  all  his  claws  ;  he  soon  learned  to  be 
a  good  deal  quicker  than  I  was,  and  if  he  got  into  his  most  favourable 
position,  I  could  not  get  the  slipper  without  some  risk.  But  it 
was  only  a  game,  and  when  it  was  over,  the  ears  came  forward  to 
their  normal  position,  the  muscles  were  relaxed,  the  claws  sheathed, 
and  the  little  fiend  became  again  a  gentle  pet.  When  young  carni- 
vores are  playing  too  roughly  with  their  mother,  she  teaches  them 
a  lesson  by  cuffing  them,  but  I  have  never  seen  her  interfering  to 
stop  a  quarrel  in  her  family,  and  not  infrequently  a  good  deal  of 
damage  is  done  as  the  excitement  of  the  game  passes  over  into 
reality.  Many  years  ago,  I  saw  by  accident  a  fatal  fight  between 
a  young  lion  and  tiger  of  about  the  same  weight  and  age.  Two 
tiger  cubs  and  a  lion  had  been  brought  up  together  in  the  same 
compartment  of  the  Lion  House  and  were  a  little  over  two  years 
old,  and  thoroughly  accustomed  to  rough  but  friendly  play. 
One  Sunday  morning,  however,  when  I  think  I  was  the  only 
visitor  in  the  Lion  House,  I  heard  a  sudden  commotion  and  ran  to 


250  CHILDHOOD  OF  ANIMALS 

see  what  was  happening.  The  tiger  (it  was  a  tigress)  had  seized 
the  lion  by  the  throat  and  was  holding  him  down.  The  other  tiger 
walked  round  and  round  the  couple,  apparently  not  much  interested, 
but  every  time  it  passed  the  outstretched  tail  of  the  lion  it  stooped 
down,  and  bit  it  in  a  casual  and  rather  bored  way.  Before  the 
keeper  could  separate  the  animals  the  lion  was  strangled.  I  do 
not  know  what  was  the  cause  of  the  dispute,  but  mimic  fights  often 
become  serious.  When  young  animals  are  beginning  to  take 
pleasure  in  their  strength,  it  is  important  that  they  should  have 
plenty  of  room  and  a  diversified  open  space  in  which  to  run  about. 
They  then  work  off  much  of  their  surplus  energy  in  chasing  each 
other,  and  are  less  disposed  to  fight  to  a  finish.  But  even  under 
natural  conditions,  usually  one  or  two  of  the  weaker  cubs  are  killed 
in  these  experimental  trials  of  strength. 

Perhaps  the  most  interesting  and  distinctive  feature  of  the  higher 
animals  when  they  are  young  is  their  faculty  of  attention.  In 
the  drawing  of  the  Springbuck  shown  on  the  plate  (XII)  the 
artist  has  caught  a  very  characteristic  attitude  of  attention.  Adult 
animals  are  alert  and  watchful.  A  sudden  sound,  a  moving  object, 
a  vibration  of  the  soil  or  the  surface  on  which  they  are  placed  at 
once  arrest  their  attention.  They  stop  chewing  or  drinking,  even 
if  they  are  hungry  or  thirsty,  cock  their  ears,  turn  their  eyes  in  the 
direction  from  which  the  disturbance  seems  to  be  coming,  and  you 
see  that  every  sense  is  on  the  alert.  Then  some  process  takes  place 
which  if  it  were  in  a  human  being  we  should  associate  with  memory 
and  judgment.  The  disturbance  is  recognised  as  something  not 
worth  troubling  about,  and  the  occupation  is  resumed,  or  it  is 
followed  by  some  action,  of  retreat  or  of  preparation  for  aggression. 
These  successive  actions  take  place  whether  they  are  accompanied 
by  some  dim  mental  phase  corresponding  in  a  faint  way  to  our 
conscious  judgment,  or  whether  they  are  like  the  unconscious  action 
of  a  sleep-walker.  Adult  animals  generally  decide  at  once  as  to 
whether  an  event  which  has  engaged  their  attention  is  of  a  kind 
to  neglect  or  of  a  kind  requiring  action.  They  do  not  show  much 
curiosity,  but,  right  or  wrong,  abide  by  their  decision  and  proceed 
with  the  business  in  hand.  They  have  stored  up  enough  experience 
and  have  no  special  wish  to  learn  anything  new.  Young  animals, 
on  the  other  hand,  are  intensely  curious,  and  the  process  by  which 
they  fit  themselves  to  th^ir  environment  can  be  watched.  My 
hyrax  was  at  first  much  disturbed  by  the  sound  of  a  clock  in 
my  room,  which  chimes  the  quarters  and  strikes  the  hours.  At 


PLATE    XII 

GROUP  OF  SPRINGBUCK  AND 
YOUNG 

Drawn  from  examples  living  in  the  London  Zoological 
Gardens  a  few  hours  after  a  kid  was  born.  The  adults 
showed  the  characteristic  attitude  of  attention  as  they 

faced  the  artist. 


XS 


ess)  had  seized 

Tig  him  down.     The  other  tiger 

:>t  much  interested, 

the  lion  it  stooped 

xer  bored  way.     Before  the 

the  lion  was  strangled.      I  do 

dispute,  but  mimic  fights  often 

img   animals    are   beginning    to    take 

important  that  they  should  have 

i  space  in  which  to  run  about. 

cjy  in  chasing  each 

But  even  under 

j  of  the  weaker  cubs  are  killed 


the  dm 

artist  h..     IjBolgsfooX  nobrtoJ  Vrfi 
animals  artf^wfajs  -KIT    .mo< 
a  vibration^1 


from  w: 


ure  of  the  higher 
In 
plate  (XII)  the 


• 

to  n 

curi</ 

with 

and  hav 

on  r  ban 

hyrax  v. 
room,  v 


at 

or  drinking,  even 
aeir  ears,  turn  their  eyes  in  the 
be  coming,  and  you 
e  process  takes  place 
ociate  with  memory 
d  as  something  not 
n  is  resumed,  or  it  is 
paration  for  aggression. 

e  actions  ta  r  they  are  accompanied 

nental  p  in  a  faint  way  to  our 

lent,  or  whet  <o  the  unconscious  action 

Adult  anim.  v  decide  at  once  as  to 

hich  has  enga^.  attention  is  of  a  kind 

ad  reqr.  do  not  show  much 

or  wrong,  abid  ir  decision  and  proceed 

d.     The  d  up  enough  experience 

h  to  lea  new.     Young  animals, 

jsely  cu»  ;d  the  process  by  which 

can  be  watched.     My 
ound  of  a  clock  in 
quarters  and  strikes  the  hours.     At 


EDUCATION  251 

first  it  would  stop  whatever  it  was  doing  when  the  sound  began; 
letting  even  a  piece  of  its  favourite  ice-wafer  drop  from  its  mouth  ; 
then  it  became  accustomed  to  the  sound  and  now  just  stops  for 
a  second  and  resumes  at  once.  I  have  tried  it  with  other  striking 
clocks,  and  it  seems  to  have  classified  all  of  them  as  harmless. 
With  the  telephone  bell  it  acts  differently,  rushing  across  the  room 
to  the  telephone  table,  climbing  up  to  the  instrument  and  waiting 
there  for  me.  I  have  tried  it  with  an  alarm  clock,  the  sound  of 
which  is  much  like  that  of  a  telephone  bell,  and  it  at  once  accepted 
that  as  one  of  the  things  to  be  run  to.  So  also  the  sound  of  passing 
motors,  of  persons  talking  in  the  adjoining  room,  were  noted, 
acquired  and  put  into  categories. 

Curiosity,  attention  and  memory  do  much  for  the  education  of 
!young  animals,  but  the  very  strange  faculty  of  imitation  also  plays 
its  part.  I  do  not  know  of  any  term  used  of  animals  that  is 
more  difficult  to  understand  or  to  apply  justly.  The  chief  difficulty 
is  that  we  are  disposed  to  interpret  the  actions  of  animals  too  much 
in  the  same  fashion  as  those  of  human  beings,  and  to  suppose  the 
presence  of  a  conscious  factor  which  may  not  exist.  When  we 
speak  of  imitation  in  human  beings,  we  think  of  the  imitator  as 
forming  an  idea  of  the  action,  and  of  that  idea  suggesting  corre- 
sponding action  on  his  own  account.  It  would  be  going  very  far 
indeed  to  assert  such  a  mental  process  in  the  case  of  animals.  Many 
cases  that  are  sometimes  set  down  to  imitation  are  no  more  than 
instances  of  similar  vital  machines  responding  in  the  same  way  to 
the  same  stimulus.  A  kitten  washes  itself  or  plays  with  a  ball 
precisely  in  the  same  fashion  whether  it  has  been  brought  up 
by  its  mother  with  its  brothers  and  sisters,  or  has  been  reared 
jaway  from  all  other  cats.  Animals  left  to  themselves  gain  the 
same  lessons  from  the  same  experiences  that  they  would  have  learnt 
in  association  with  their  kind.  I  do  not  doubt  but  that  my  hyrax 
climbs  at  least  as  well  as  if  it  had  been  running  with  its  mother  in 
the  tree-tops.  The  fact  that  so  many  young  animals  follow  their 
mother  accounts  for  many  of  the  circumstances  that  look  like  imita- 
tion. When  she  runs,  they  run  after  her,  and  it  is  only  by  experience 
that  they  learn  to  associate  with  running  the  stimulus  that  made 
the  mother  run.  They  run,  not  because  they  are  imitating  her 
action,  but  because  it  is  their  habit  to  run  after  her.  So  also  when 
she  leads  them  to  the  proper  food,  and  they  follow  her  example 
by  eating  it,  all  that  it  is  necessary  to  suppose  has  happened  is 
that  the  food  stimulus  to  which  they  have  been  led  excites  them 


252  CHILDHOOD  OF  ANIMALS 

to  the  same  action  as  it  excites  their  mother.  Nor  does  the  common 
action  of  gregarious  animals  really  imply  imitation.  The  playful 
stampedes  of  cattle,  the  game  of  "  follow  my  leader  "  indulged  in 
by  sheep  and  goats  and  antelopes,  the  migrations  of  mammals  and 
birds  do  not  necessarily  mean  more  than  similar  response  to  similar 
stimulation. 

Nevertheless  there  are  many  facts  which  make  it  difficult  to 
doubt  that  the  higher  animals,  especially  when  they  are  young, 
perform  actions,  consciously  or  unconsciously,  because  they  hava 
just  been  performed  by  other  animals  or  by  human  beings.  I  do 
not  think  that  this  happens  whilst  the  young  creatures  are  quite 
infantile,  but  only  after  the  period  which  is  well  described  as  "  begin- 
ning to  take  notice. "  The  action  must  be  more  or  less  like  one 
that  the  animal  would  naturally  do,  or  if  it  be  complicated,  it  must 
be  built  up  step  by  step  out  of  separate  actions  which  are  not  too 
unfamiliar  or  incongruous  with  natural  habits.  I  picture,  rather 
than  explain,  the  process  to  myself  by  supposing  that  in  animals 
with  well-developed  grey  matter  in  the  brain  actions  write  some 
sort  of  record  of  themselves  in  the  brain,  apart  from  the  necessary 
reflex  brain-and-muscle  mechanism  by  which  they  are  controlled. 
This  record  can  be  excited  in  various  ways,  and  its  excitement  may 
set  going  the  actual  mechanism.  When  the  young  animal's  atten- 
tion and  curiosity  are  aroused  by  the  action  of  another  animal, 
the  records  already  stored  in  its  brain  are  awakened,  and  the  most 
closely  corresponding  reflex  mechanisms  are  "  called  up  "  and  set 
going.  Consciousness  is  not  necessarily  involved,  but  the  process 
is  a  result  of  organic  memory. 

However  it  be  explained,  action  which  is  the  result  of  a  corre- 
sponding action  becomes  increasingly  important  in  the  higher 
animals.  Wild  animals  acquire  or  at  least  perfect  many  of  their 
capacities  in  this  way.  The  process  of  taming  and  training  animals 
is  based  on  it.  How  far  birds  learn  from  one  another  or  from  their 
elders  I  do  not  know,  and  it  is  a  much  disputed  question.  It  seems 
to  be  fairly  certain  that  building  of  nests  does  not  come  about  by 
any  process  that  may  be  called  imitation,  and  that  birds  reared 
by  hand  or  away  from  their  allies  will  in  due  course  build  according 
to  the  pattern  of  their  kind,  although  their  first  attempts  may  not 
be  so  good  as  later  efforts.  The  ordinary  call-notes  and  narrow 
range  of  voice  that  occur  in  most  of  the  families  of  birds  are  similarly 
inborn,  but  the  higher  and  more  complicated  kinds  of  song  certainly 
owe  much  to  practice  and  emulation.  Singing  birds  that  are  reared 


EDUCATION  253 

away  from  their  kind  achieve  only  a  feeble  and  halting  song,  but 
rapidly  acquire  elaboration  and  richness  when  they  hear  others 
singing.  There  is  a  kind  of  local  tradition  of  song,  and  now  and 
again  you  will  find  a  wood  resonant,  season  after  season,  with 
songsters  of  a  more  mellowed  sweetness,  due  to  the  example  of 
some  genius  amongst  them.  Our  own  mtell  gence  is  so  remote 
from  that  of  birds  that  we  come  into  little  organic  contact  with 
them,  and  I  doubt  if  birds  ever  imitate  human  beings  except  in 
sound,  and  it  is  certainly  ridiculous  to  suppose  that  the  cleverest 
talking  birds  have  any  consciousness  of  the  occasional  appropriate- 
ness of  their  remarks. 

With  mammals  we  own  kinship  in  every  fibre  of  our  bodies  and 
we  can  establish  i  elations  with  them  in  many  different  ways.  Their 
senses  of  smell,  taste,  touch,  sight  and  hearing,  their  muscular 
movements  and  reflexes,  their  passions  and  their  pleasures,  the 
instincts  with  which  they  start  life  and  their  mode  of  modifying 
them,  are  all  like  our  own.  This  very  similarity  makes  it  difficult 
not  to  confuse  between  real  imitation  and  corresponding  action 
in  corresponding  circumstances.  There  seems  no  conceivable 
doubt  about  imitation,  however,  in  the  case  of  man  and  the  great 
apes.  Chimpanzees  and  orangs  watch  what  is  happening  round 
about  them.  If  you  take  a  wooden  match-box  out  of  your  pocket 
and  open  and  shut  it,  and  then  give  it  to  one  of  them,  it  will  try 
to  repeat  the  movement.  They  copy  their  keeper  in  sweeping  out 
their  cage.  They  are  taught  many  kinds  of  tricks  and  perform- 
ances almost  as  much  by  doing  the  various  motions  required  in 
front  of  them  as  by  actually  guiding  them.  They  will  run  when 
you  run,  danc  when  you  dance,  shoot  out  their  lips  and  scream 
when  you  set  them  the  example.  No  doubt  there  is  a  pitfall  even 
here.  Monkeys  are,  as  it  were,  caricatures  of  human  beings  ;  in 
a  sense  they  ape  man,  although  they  may  never  have  seen  him.  I 
am  convinced  however,  that  they  constantly  perform  new  actions 
because  similar  action  have  been  carried  out  in  their  sight,  and 
I  find  it  difficult  to  avoid  the  belief  that  the  anthropoid  apes  at 
least  have  some  dim  consciousness  of  what  they  are  about.  Not- 
withstanding the  innumerable  anecdotes  about  the  intelligence 
of  other  mammals,  and  the  great  difficulty  there  is  in  describing 
or  even  thinking  over  one's  own  personal  experience  in  taming 
and  training  animals  without  slipping  into  language  that  implies 
conscious  imitation,  I  do  not  think  that  there  is  any  real  evidence 
for  it  outside  the  group  of  monkeys.  Curiosity,  attention  and 


254  CHILDHOOD  OF  ANIMALS 

organic  memory  seem  to  me  to  account  for  all  the  facts,  and  it 
must  be  remembered  that  even  the  word  curiosity  is  a  dubious 
term.  It  may  mean  no  more  than  that  the  senses  are  alert  to  any 
stimulation,  and  that  stimulation  is  followed  by  action  directed 
towards  the  source  of  the  stimulus. 

This  may  seem  a  doubtful  end  to  an  argument,  and  a  cold  con- 
clusion for  one  who  is  a  lover  of  animals.  The  trouble  lies  in  the 
word  consciousness.  In  my  opinion  instincts,  experimental  action, 
experience,  memory  with  its  consequence — choice  of  motives  for 
action,  the  immediate  and  the  remembered — states  of  pleasure 
and  pain,  all  may  precede  consciousness.  Consciousness  is  some- 
thing apart  from  them,  different  from  them,  probably  dimly  begin- 
ning in  the  lower  animals,  a  little  clearer  in  the  apes,  still  clearer 
in  savages,  but  even  in  ourselves  intermittent,  and  at  its  best  much 
less  complete  than  we  think. 

If,  however,  we  remember  that  the  terms  we  employ  must  gain 
or  lose  colour  and  change  their  significance  according  to  the  extent 
to  which  we  are  willing  to  suppose  consciousness  involved,  then 
there  is  no  doubt  about  the  facts.  The  reason  why  the  higher 
animals  have  a  long  period  of  youth  is  that  instinctive  action  may 
be  replaced  by  action  based  on  experience,  upon  the  remembered 
results  of  experiment.  For  this  purpose  they  are  fed  and  protected, 
freed  from  the  cares  of  the  world  and  shielded  from  its  troubles, 
dowered  with  an  excess  of  energy  and  a  fund  of  high  spirits.  When 
adult,  independent  life  is  reached,  there  is  seldom  time  for  reflection 
or  experiment.  The  business  of  life  is  to  meet  a  continuous  series 
of  emergencies  by  prompt  and  unhesitating  action,  and  this  is 
accomplished  best  by  those  animals  that  have  had  the  longest 
youth,  the  best  opportunity  for  playing  at  life  whilst  it  was  still  a 
game,  and  for  making  mistakes  when  mistakes  mattered  least. 

The  mental  field  of  youth  and  especially  of  our  own  youth  is 
sometimes  spoken  of  as  a  tabula  rasa,  a  clean  sheet  upon  which 
anything  may  be  written.  Nothing  is  further  from  the  truth.  In 
young  animals  and  in  ourselves  it  is  a  blend  of  all  sorts  of  inherited 
instincts  and  aptitudes,  and  we  have  gained  the  tremendous  advan- 
tage over  other  animals  and  over  the  lower  members  of  our  own 
race,  that  we  have  a  prolonged  time  for  finding  out  and  developing 
the  aptitudes  and  for  modifying  the  instincts.  O  r  own  youth 
should  be  devoted  to  this  natural  purpose.  What  is  called  technical 
education,  the  training  for  a  special  avocation,  the  development 
of  an  aptitude  for  a  special  calling,  should  be  put  off  as  long  as 


EDUCATION  255 

possible.  The  infant  prodigy,  and  the  youth  who  quickly  finds  out 
one  thing  that  interests  him  and  plods  successfully  at  it,  represent 
lower  and  older  types,  grades  in  the  evolution  of  man  which  are 
being  discarded.  Youth  should  be  spent  in  blunting  every  instinct, 
in  awakening  and  stimulating  every  curiosity,  in  the  gayest  roving, 
in  the  wildest  experiment.  Education  should  be  a  parade  of  all 
handicrafts,  of  all  mental  and  emotional  stimulations,  of  the  arts 
and  sciences,  and  the  last  thing  to  be  considered  is  what  is  practically 
useful.  The  supreme  duty  of  youth  is  to  try  all  things,  to  experi- 
ment with  everything,  to  be  scatter-brained  rather  than  con- 
centrated. In  due  time  the  world  will  certainly  close  round  and 
press  each  beginner  of  life  in  one  direction,  but  he  will  meet  the 
pressure  most  successfully  who  has  remained  young  longest  and 
who  has  stored  up  the  most  varied  experience. 


INDEX 


ADAPTATIONS,  105,  155 

Adder,  2,  146 

Advertisement,  coloration  as,  73 

Affection,  origin  of,  131 

Afterbirth,  166 

Agoraphobia,  234 

Agouti,  220 

Albatross,  104 

Albumin  in  milk,  185 

Alcohol,  1 86,  234,  236 

Alligator,  144,  196 

Alpaca,  46,  93,  218 

Alytes,  brood-care,  141 

Amblystoma,  60 

Amoeba,  5,  233 

Amphiuma,  breeding  habits,  140 

Anaconda,  197 

Ancestral  and  adaptive  characters,  8, 

223 

Andrena,  33 

Angler,  marbled,  nesting  habits,  137 
Aniline  dyes,  112 
Animalcula,  tropisms  of,  234,  235 
Anteaters,  163,  178,  220 
Antelopes,  46,  75, 115,  170,  171,  219 

American,  91 

angas,  91 

striped,  78 

tragelaphine,  89 

coloration,  88 

rump  patches,  71 

sexual  coloration,  69 

skin  glands,  184 
Antennarius  marmoratus,  137 
Anthophora,  33 
Antlers  of  deer,  12,  46 
Ants,  73,  128,  132,  205 

C.A. 


Ants,  white,  125 

Anura,  18 

Apes,  consciousness,  253 

milk  of,  1 88 

tricks  of,  253 

anthropoid,  38,  39, 148, 165 
Aphides,  133 
Appetite,  193 
Apteryx,  104,  153 
Aquarium,  233 
Aristotle,  137 
Armadillo,  81,  179,  220 
Armour  of  extinct  mammals,  81 
Arrau-turtle,  143 
Arthropods,  30 
Ascidian,  20 

Ash  of  milk  and  flesh,  186 
16,      Aspredo,  138 

Asses,  45,  75,  95,  172,  217 
Attention,  202,  250 
Auk,  149,  154 
Automatism,  6,  228,  229 
Avocet,  1 02 
Axis  deer,  92 
Axolotl,  60 

> 

BABIRUSSA,  93 
Baboons,  longevity,  39 
Background,  patterns  matching,  78 
Bacteria  as  external  parasites,  82 
Bactrian  camel,  93 
Badgers,  42,  79,  87,  169 
Bandicoot,  129 
Banteng,  88 
Barasingha  deer,  92 
Barbets,  153 

Barley-water  for  diluting  milk,  191 
257  R 


258 


INDEX 


Basket- work,  151 

Bates,  H.  W.,  73 

Batrachians,  15,  48,  51,  59,  60,  70,  140 

Bears,  10,  42,  86,  194 

Polar,  1 68,  169,  243 
Beaver,  46,  176,  177,  220 
Bee-eater,  153 

Bees,  33,  55,  72.  73,  "7,  132,  205 
Beetles,  33,  70,  128 
Beisa,  89 

Berries  of  lobster,  121 
Binturong,  85 
Bipinnaria  larva,  23 
Birds, 

ancestors,  159,  240 
brood-care,  147 
domesticated,  204 
down  of,  97,  101 
duration  of  youth,  49 
eggs  of,  147 
feeding  young,  242 
imitation  by,  252 
insectivorous,  72,  161 
intelligence,  50 
learning  to  walk,  240 
limitation  of  family,  148 
longevity,  49 
patterns,  79 
preen-gland,  184 
sexual  coloration,  69 
size  and  longevity,  49 
skin  glands,  184 
talking,  253 

Birds-of-paradise,  49,  62,  66, 69, 109 
Birds-of-prey,  49,  105,  no,  150,  152,  153, 

154,  242 
Bison,  46,  115 
Bitterling,  138 
Bittern,  153 
Bivium,  119 
Blenny,  138 

Blood,  63,  156,  214,  225 
Blow-fly,  31 
Blubber,  243 
Blunt,  Captain  E.,  56 
Boa,  146 
Bonavia,  Dr.,  81 
Bongo,  91 
Bontebok,  88 


Bottle-feeding,  243 

Bow-fin,  136 

Brain,  convolutions  of,  226 

development  of,  226,  227 

grey  matter,  226 

and  imitation,  252 

of  Primates,  figured,  227 

as  storehouse  of  experience,  237 

structure  of,  226 

and  duration  of  youth,  41 
Brain-growth  in  youth,  229 
Breeding  plumage,  79,  1 12 
Breeding  season,  colours  of,  69,  113 
Bristle-tail,  33 
Brittle  star,  120 
Brocket-deer,  92 
Brood-care,  120 

in  birds,  145,  159 

in  frogs  and  toads,  140 

in  mammals,  163 

in  rodents,  176 

in  spiders,  122 

in  lower  vertebrates,  134 
Brood-pouches,  121 

Brush  turkey,  97,  102,  107,  150,  159,  194 
Budgett,  J.  S.,  135 
Buffalo,  170 
Bufoy  170 
Bugs,  70,  82 
Bullhead,  136 
Bustard,  101,  154 
Butter,  1 86 
Butterfish,  135 
Butterflies,  55, 70,  73,  118^ 
Button  quails,  70,  109, 154 

CALVES  of  ruminants,  171 
Camel,  n,  46,  93,  171,  218 
Campodeiform  larva,  33,  55 
Canary,  205 
Cane-sugar,  186 
Cannibal  larvae,  132 
Captivity,  effects  of,  207,  220 
Capybara,  175, 220 
Caracal,  10,  41,  85 

tame,  42,  213,  230,  247,  248, 249 
Care,  parental,  118,  168,  245 
Cariama,  154 
Carnivores,  boxing  of,  233 


INDEX 


259 


Carnivores,  breeding,  41,  166 

characters,  42 

domesticated,  204 

cubs,  169 

games,  228 

habits  at  night,  213 

handling  of,  219 

size  and  intelligence,  43 

milk,  1 88,  190 

nervousness  of,  213 

sexual  coloration,  69 

taming  of,  210,  211 

young,  10 

and  ungulates,  173 

vegetarian,  169 
Carp,  205 

Cassowary,  70, 101,  106,  109, 149, 154, 161 
Castor-oil,  194 

Caterpillars,  3,  32,  75,  76,  127,  224,  230 
Cat-fish,  137 
Cats,  10,  41,  84,  231 
Cattle,  46,  88,  171,  219 
Cells,  of  brain,  226,  227 

in  embryology,  223 

as  units  of  structure,  65 
Cerebrum,  231 
Cereopsis,  106 
Chameleon,  viviparous,  145 
Chamois,  88,  171 
Chauna,  104 
Cheetah,  85 

Chemistry    compared    with  vital   func- 
tions, 232 
Chemotropism,  234 
Chevrotain,  93 
Chicks,  precocious,  101 
Childhood,  definition  of,  i 

summary  of  characters,  223 
Chimpanzee,  ancestor  of,  7 

fear  of  snakes,  201 

gait  of,  241 

and  imitation,  253 

longevity,  38 

performing,  209 

taming  of,  208 

trained,  221 
Chrysalid,  3,  32 
Cicada,  seventeen-year,  56 
Cichlids,  brood-care,  138 


Circus-performing  elephants,  44 

Civets,  10,  85 

Civilisation  of  ants,  132 

Cladocera,  brood-care,  120 

Claustrophobia,  234 

Claws  of  young  carnivores,  212 

Cleanliness,  in  apes,  210 

of  carnivores,  211 

of  hyrax,  216 

of  nests,  161 

of  ungulates,  216 
Cliff- swallow,  nest  of,  151 
Coal-tar,  112 
Coati,  87 
Cockatoo,  199 

Cockroach,  34,  124,  205,  233 
Cocoon,  122,  124,  130 
Cod,  117,  134 
Ccecilian,  140 
Cold,  effect  of,  162,  168 
Colics,  153 
Colonies,  of  ants,  133 

birds,  152 

termites,  125 
Coloration,  definition  of,  63 

summary  of,  68,  112 

of  birds,  103,  113 

concealing,  74,  104,  114 

of  deer,  72 

of  down,  104 

of  eggs,  154,  155 

of  mammals,  81 

protective,  78,  224 

sexual,  70 

warning,  72,  74,  75 
Colour,  62,  66,  67,  112 
Communities,  of  ants,  128,  133 

bees,  132 

social  insects,  132 

termites,  125,  132 

wasps,  132 
Companionship,  loss  of,  67 

animals,  168,  211 

Concealment  by  coloration,  78,  96,  1 14 
Condor,  49,  105,  108 
Coney,  95,  216 

Consciousness,  233,  237,  251-253 
Conspicuousness,  69 
Contour-feathers,  97,  98 


260  INDEX 

Control,  power  of,  239,  243 

Convolution  of  brain,  225 

Coots,  104 

Cormorants,  102,  103,  153,  162 

Countershading,  75-78,  88,  97 

Coursers,  154 

Cowbirds,  148,  157,  190 

Coypu,  178 

Crabs,  30,  121 

Cranes,  101,  154 

Crayfish,  15 

Cream,  186 

Crocodiles,  15,  144,  145,  184,  166 

Crows,  150 

Crustaceans,  27,  30,  34,  118,  120 

Cubs,  10,  1 68,  190 

Cuckoo,  102,  in,  149,  153,  154,  157 

Cud,  188 

Curassow,  153 

Curd,  188 

Curel,  F.  de,  231 

Curiosity,  250,  253 

Curlew,  102 

Cygnet,  240 

DARWIN,  36,  70,  72,  113,  115 

Dassie,  44, 173 

Dasyure,  96 

Death  and  young  animals,  116 

Death-rate  of    sparrows    and     human 

beings,  116 
Deer,  75,  77 

antler-growth  in,  12 

coloration,  91 

duration  of  youth,  46 

milk  for,  190 

rump  patches,  71 

sexual  colours,  69 

skin  glands,  184 

spotted,  78 

lameness  of  young,  219 

young,  171 
Demersal  eggs,  135 
Deniker,  J.,  9 
"  Descent  of  Man,"  70 
Desert  animals,  77 

Development,    embryological,    of  indi- 
viduals, 223 
Devil,  Tasmanian,  180,  220 


Diatoms,  232 
Digestion,  183,  198 
Dik-dik  antelope,  89 
Dipleurula  larva,  23 
Display  of  cock  pheasants,  71 
Divers,  102,  154 
Dog-fish,  138 
Dogs,  coloration,  86 

duration  of  youth,  42 

habits  of  young,  247 

qualities  of,  205 

skin  glands,  184 
Dolphins,  240 

Domestic  animals,  48,  75,  204 
Domestication,  204,  205,  221 
Doves,  in 

Down  feathers,  97,  98,  101-105,  X59 
Dragonflies,  56,  70,  125 
Drakes,  69,  109 
Dromedary,  ii,  93 
Duck-billed  mole,  163 
Ducklings,  102,  161,  240 
Ducks,  coloration  of  young,  104,  106 

colour  of  eggs,  153 

fledging  of,  108 

longevity  of,  49 

plumages  of,  98,  100,  103,  109 

South  American,  112 
Duckweed,  161 
Dugong,  240 
Duikers,  46,  88,  89 
Duration  of  youth,  37,  49,  54,  112 

EAGLES,  49,  102, 103,  105 

Earthworm,  120 

Earwig,  34, 124 

Eat,  learning  to,  242 

Echidna,  2 

Echinoderms,  22,  23 

Eclectus,  64,  101,  in 

"  Eclipse"  plumage,  99,  100,  no,  112 

Edentates,  220 

Education,  37,  48,  169,  239, 255 

Eels,  53,  54,  233 

Egg-cell,  222 

Eggs,  of  birds,  colours,  153,  154 

incubation,  101 

laying  of,  148,  149 

shapes  of,  152 


INDEX 


Eggs,  butterflies,  129 

fish,  52,  115,  130,  134,  138 

mammals,  163 

marine  animals,  117 

reptiles,  142,  145,  163 
Elands,  46,  go,  219 
Elasmobranch,  138 
Eld's  deer,  92 
Elephants,  breeding,  115,  173 

domestication,  216 

duration  of  youth,  43 

intelligence,  44 

size  and  weight,  43 

skin  gland,  184 

taming,  216 

training,  44 

young,  n,  95 
Elephant-seal,  194,  214 
Elk,  46,  92 
Embryology,  222 
Embryos,  129,  139,  142,  163,  224 
Emotions,  182 

Emu,  101,  105,  149,  154,  161,  182 
Endowment,  natural,  229 
Environment,  223,  238 
Evolution,  36,  222,  223,  239 
Excretion,  67,  113,  161 
Experience,  235-237,  239, 242,  245 

FAMILY,  limitation  of,  115,  118,  131, 134, 

142,  148 
Fantang,  136 

Fascination  by  snakes,  202 
Fatigue,  230 
Fat  in  milk,  186 
Fawns,  219 
Fear,  of  man,  214 

of  snakes,  200 
Feathers,  83,  97,  98 
Feeding,  artificial,  190 

by  spoon,  189 

of  reptiles,  197 

of  young  animals,  188 
Feeding-bottles,  189 
Females  with  male  plumage,  70,  109 
Ferrets,  169 
Fieldmouse,  175 
Fight,  lion  and  tiger,  249 
Fighting  of  young  animals,  249 


Finches,  food  of  young,  161 

nests  of,  156 
Fish,  ancestral  history,  21 

annual  rings,  52 

brood-care,  139 

contact  reactions,  233 

development  of,  222 

eggs  o^  52 

fertility,  134 

instincts  modified  by  brood -care,  139 

mucous  glands  of,  184 

rate  of  growth,  51 

sexual  coloration,  70 

temperature  of,  50 

typical  shape  of,  21 
Fish-lice,  brood-care,  120 
Flamingo,  49,  104,  in,  151, 1 53 
Flat-fish,  metamorphosis,  21 
Fleas  as  parasites,  82 
Flies,  green,  54 
Flight  of  birds,  97,  242 
Fly,  31,  55 
Fly-catcher,  in 
Foals,  94,  172 
Foetus,  9 

Fontainebleau,  205 

Food,  48,  161,  183,  1 88,  194,  236, 239, 242 
Forest  animals,  77 
Fossils,  64 

Fowls,  69,  107,  108,  222 
Fox,  86 
Freewill,  237 

Freiburg,  University  of,  60 
Frigate-birds,  153 
Frog-mouth,  153 

Frogs,  15,  17,  51,  59,  75,  140,  184,  231 
Fruit-pigeon,  m 
Fur,  83 
Fur-seal,  42 

GAHAN,  C.  J.,  56 

Gall-flies,  127 

Gall-midges,  59 

Game-birds,  101,  103,  106,  112,  153 

Games  of  young  animals,  246 

Gannets,  102,  116 

Garden-spider,  122 

Gayal,  88 

Gazelles,  89,  219,  247 


262 


INDEX 


Geese,  coloration  of  young,  104, 106 

colour  of  egg,  153 

fledging  of,  108 

longevity,  49 
Genets,  85 
Gharial,  144 
Gibbons,  38,  201,  209 
Gills,  17,  19 

Giraffe,  4,  n,  46,  91,  171 
Glands,  mammary,  183,  185 

sebaceous,  185 

skin  glands  in  different  animals,  184 

sweat,  185 
Glochidium,  129 
Glutton,  87 
Gnu,  88,  219 

Goats,  75,  88,  170,  219,  247 
Goat-sucker,  169 
Goldfish,  205 

Gorilla,  7,  8,  38,  40,  207,  208 
Grades  of  coloration,  69 
Grape-sugar,  186     * 
Grasshopper,  124 
Grass-snake,  184 
Grebes,  102,  106,  153,  160 
Green,  attraction  of  young  mammals  for, 

243 

Green-fly,  54 

Green  plants,  food  o£  183 
Gregarious  animals,  71 
Gregariousness,  145,  177,  207,  252 
Greyhound,  duration  of  youth,  42 
Grey  matter  of  brain,  229,  237 
Grilse,  53 

Grizzly  bear,  moult  of,  86 
Groos,  Professor,  246 
Ground-parrot,  nest,  149 
Growth-patterns,  65,  105 
Growth,  rate  of,  47,  48,  223 
Grubs,  127,  128 
Guemal  deer,  coloration,  92 
Guillemots,  colour  of  eggs,  154 
Guinea-pigs,  46,  176 
Gulf  Stream,  137 
Gulls,  coloration  of  young,  102,  107 

colour  of  eggs,  154 
I          food  of  young,  162 

learning  to  swim,  240 


i 


longevity  of,  49 


Gymnarchus  nilotictts,  136 

HAGENBECK,  Carl,  101,  212 

Hag-fish,  secretion  of  mucus,  184 

Hair  of  immature  animals,  Si 

Hammerkop,  150 

Hamsters,  176 

Hand-feeding,  189 

Handling  of  young  animals,  219 

Hare,  3,  46,  75,  77,  78,  176,  178 

Hartebeeste,  88 

Harvest-mouse,  176 

Hawfinch,  nest  of,  150 

Hawks,  young,  102,  103 

Heat,  radiation  of,  67 

Hedgehog,  175,  220 

Hemipode,  plumage  of  female,  109 

Hen  pheasants,  plumage  of,  108 

Herbivores,  milk  of,  187 

Herons,  150 

Herring,  117,  135,  222 

Hessian-fly,  59 

Heterotis  niloticus,  nesting  habits,  136 

Hibernation  of  polar  bear,  168 

Hippocampus,  brood-pouch  figured,  137 

Hippopotamus,  n,  45,  93,  171,  172,  175, 

218 

Hoatzin,  241 
Hog-deer,  92 
Hog,  pygmy,  93 
Hoopoo,  149,  154 
Hornbill,  103,  149,  151,  153,  158 
Horns,  12,  13 

Horses,  45,  81,  93,  95,  172,  184, 190,  217 
Huanaco,  93,  218 
Hudson,  W.  H.,  148 
Human  death-rate,  116 
Human  race,  182 
Humming-bird,  49,  103 
Hunger,  168,  188 
Hunting-spider,  122 
Hyaenas,  10,  86 
Hydra,  232,  236 
Hyla,  140,  142 
Hyrax,  173,  184 

tame,  44,  216,  241,  247,  250,  251 

IBIS,  no,  154 
Ichneumon-flies,  127 


INDEX 


263 


Ichneumons,  85 

Imitation,  251-253 

Incubation,  101,  145, 156-158 

Insectivora,  175,  220 

Insects,  31,  34,  54,  55,  58,  123,  233 

Instincts,  55,  131,  152,  166,  221,  229-239, 

242,  243,  254 

Institution,  Royal,  199,  200 
Intellect,  182 
Intelligence,  and  duration  of  youth,  41 

and  instinct,  229 

of  birds,  50 

of  insects,  55 
Intestines,  187 
Invertebrates,  temperature  of,  50 

JACAMAR,  153 

Jackal,  86 

Jaguar,  10,  41,  75,  78,  81,  85 

Japanese  ape,  39,  165 

deer,  92 

Jardin  des  Plantes,  60 
Jelly-fish,  118 
Judgment,  250 
Jungle-fowl,  106 

KAKAPO,  149 

Kaleidoscope,  64 

Kangaroo,  3,  46,  75,  77,  164,  179,  241 

Kephir,  186 

"  Khaki,"  78 

Kingfishers,  100,  102,  103,  HI,  149,  153 

King-penguin,  no 

Kittens,  3,  190 

Klipspringer,  89 

Koala,  181 

Kob,  89 

Kumiss,  186 

LANDSNAILS,  130 

Langur  monkey,  165 

Lapwing,  99 

Lark,  103 

Larvae,  17,  18,  19,  36,  117,  224 

of  ascidian,  19 

of  blow-fly,  31 

campodeiform,  55 

echinoderm,  22 

of  eels,  53 


Larvas,  of  fish,  52 

of  mussel,  129 

Lavatory,  chimpanzee  and,  210 
Leaf-insect,  124 

Leaves  chosen  by  mammals,  243 
Leeches,  120 
Lemmings,  178 
Lemurs,  83,  166,  167,  184,  200 
Leopards,  10,  41,  75,  78,  81,  85,  213 
Leptocephali,  53 
Lice,  82 

Life,  family,  in  invertebrates,  132 
Light,  77,  232 
Limitation  of  families,  118 
Limpet,  130 
Linsang,  85 

Lion,  10,  41,  62,  75,  84,  85,  166,  249 
Litter,  193 
Lizards,  15,  75 

breeding,  145 

food,  72,  195 

sexual  coloration,  70 

skin  glands,  184 

viviparous,  145 
Llama,  46,  93,  218 
Loach,  130 
Lobster,  121 
Locomotion,  239 
Locust,  35,  124 

London,  birds  in  the  parks,  207 
Longevity  and  duration  of  youth,  40 
Lumpsucker,  135 
Lungfish,  17,  67,  13 
Lynx,  10,  41,  84,  85 

MACAQUES,  39 

Mackerel,  117 

Madness,  228 

Mammals,  armour  of  extinct,  8l 

birth  of,  165 

brood-care,  163 

coloration,  97 

compared  with  birds,  49 

duration  of  youth,  37 

geological  age  of,  163 

learning  to  feed,  243 

moult  of,  82 

patterns  of,  96 

size  of,  47 


264 


INDEX 


Mammals,  skin  glands,  184 

summary  of  relations  to  young,  182 

weaning  of,  191 
Mammary  glands,  183 
Mammoth,  n 
Manatees,  240 
Mandrills,  39 

Mansbridge,  keeper  at  Zoological  Gar- 
dens, 209 
Mantis,  124 
Mares,  milk  of,  186 
Marmosets,  166 
Marsupials,  2, 179,  182 

coloration,  95 

duration  of  youth,  46 

eggs  of,  163 

low  intelligence  of^  220 
Marsupium,  2,  179 
Marten,  42 
Martin,  161 
Mastiff,  42 
Mayflies,  55,  125 
Meals,  intervals  between,  188 
Meat,  raw,  use  of,  191 
Medicine,  administration  of,  189 
Megapodes,  150,  159 
Memory,  221,  237,  250,  252 
Menageries,  wild  animals  in,  205 
Mendel,  74 

Mental  capacity  and  duration  of  youth, 
4i 

qualities,  229 

Metamorphosis,  17, 1 8,  19,  59,  60 
Metchnikoff,  Professor  E.,  9,  58,  229 
Mice,  47,  176,  178 
Microbes,  234 
Microscope,  117 
Migrations,  177 

Milk,  166,  185,  186,  187,  188, 190, 191 
Milk-glands,  183 

Milk-sugar,  186  1 

Mimicry,  73,  74 
Mind,  229 
Mink,  87 
Minnow,  130 
Mirror  and  pattern,  64 
Model  to  show  countershading,  77 
Models  in  mimicry,  73,  74 
Mole,  175 


Mole,  duck-billed,  163 

Mole-cricket,  125 

Molluscs,  26,  118,  129,  130 

Molobrus,  148 

Monkeys,  and  domestication,  204 

as  caricatures  of  human  beings,  253 

as  egg-stealers,  148 

coloration  of  young,  83 

diet  of,  192 

distinctive  habits,  246 

fear  of  snakes,  200 

fur  of  young,  83 

gait  of,  241 

milk  for,  190 

milk  of,  188 

mode  of  handling,  210 

moult,  83 

sexual  colours,  69 
Moorhen,  104,  241 
Mortality  of  young,  224 
Mosaic,  body  as,  68 
Moths,  31,  55,  70,  73,  75,  153 
Moulds,  82 
Moult,  of  birds,  98-103,  108 

in  birds  and  mammals,  83 

and  coloration,  69 

of  down,  107 

of  mammals,  82,  84,  86,  87,  88,  96 

and  plumage  change,  99 

of  quills,  98 

of  spiders,  122 
Mouse-deer,  93 
Mucus,  secretion  of,  184 
Mule-deer,  92 
Miiller,  F.,  73 
Mungoose,  85 
Muntjac,  92 
Muscle-nerve,  236 
Museum,  British,  56,  102 
Musk-deer,  92 
Mussel,  129 
Mynah,  199 
Mysis  larva,  29 

NATURAL  selection,  113 
Nature,  absence  of  purpose,  63 

prodigality  of,  224 
Nauplius  figured,  29 
Nekrophobia,  234 


INDEX 


265 


Nestlings,  14,  101-103,  159,  160,  241 
Nests,  of  birds,  101,  149-152,  158 

fishes,  135 

mammals,  176 

spiders,  122 

Newts,  2,  15,  17,  70,  184 
Night,  effect  on  carnivores,  213 
Nightjars,  154 
Nilgai,  91 
Nipple,  189,  242 
Nototrema,  142 

OIL-BEETLE,  33 

Operations  on  animals,  189 

Opossum,  181 

Orang,  7,  38,  194,  201,  208,  241,  253 

Organs,  larval,  224 

Oribi,  89 

Orioles,  in 

Oryx  antelope,  89 

Osprey,  105 

Ostrich,  coloration  of  chick,  104 

duration  of  youth,  49 

eggs  of,  101 

food  of  young,  161 

longevity  of,  49 

presence  of  quills,  97 

sexual  coloration  69 

South  American,  105 
Otoliths  of  fish,  52 
Otter,  42,  87 
Ovary  of  fishes,  138 
Oven-birds,  148,  151 
Ovipositor,  124,  127,  138 
Owls,  49,  102,  105,  in,  149,  153 
Oxygen,  234 
Oyster,  63,  129 
Oyster-catcher,  79 


PAINTS,  scaling,  82 
Paludina,  130 
Pampas  deer,  92 
Panda,  87 
Pangolin,  179 
Parasites,  58,  82,  192 
Parasitism,  149 
Parental  care,  118,  161,  262 
Parr,  52 


Parrots,  49,  64,  100,  102,  in,  149,  153, 

161 

Partridges,  106,  108 
Pattern,  in  animals,  62 

in  birds,  112 

conspicuous,  75 

growth,  8 1 

of  mammals,  81,  96 

origin  of,  113 

primitive,  113 

as  repetition  of  parts,  64 

rupture,  78,  96 

secant,  78 

spotted,  8 1 

striped,  81 

of  young  animals,  224 
Peacock,  "  eyes  "  in  tails,  76 

pheasant,  71 

sexual  coloration,  69 
Peat-moss,  193 
Peccaries,  45,  171,  184,  218 
Peckham,  Mr.  and  Mrs.,  235 
Peewit,  99 
Pelage,  87,  96 

Pelicans,  49,  104,  110,  153,  162 
Penguins,  63,  97,  102,  104,  107,  no,  149, 

i53»  157 

Perennibranchs,  60 
Performing  animals,  212 
Pets,  213,  216 
Petrels,  102,  149,  154,  162 
Phalarope,  70,  109 
Pheasants,  69,  71,  106,  108,  241 
Pholis,  135 
Phototaxis,  232 
Phototropism,  232 
Phyllomedusa,  141 

Pigeons,  49,  101-103,  m,  150*  ^S*  163 
Pigments,  66,  154 

igs,  46,  93,  164,  171,  175 
Pike,  233 
Pipe-fish,  137 
Placenta,  138,  139 
Plant-lice,  54 

Plants,  reaction  to  light,  232 
Platypus,  2 
Plovers,  1 02 

Plumage,  breeding,  99,  112 
coloration  of,  104 


266 

Plumage,  "eclipse,"  no,  112 

of  nestlings,  78,  102,  107 

sexual,  69,  no 

successive,  99,  108 
Pocock,  R.  I.,  198 
Pointer,  42 

Poisonous  plants,  244 
Polar  bears,  42,  77,  86,  168,  169 
Polecat,  42, 87,  169 
Polygordius,  24,  25 
Polyps,  117,233 
Pompilidae,  128 
Pond -snail,  130 
Pond-tortoise,  143 
Porcupine,  176 
Porphyrio,  241 
Porpoise,  75,  240 
Poulton,  Professor  E.  B.,  76 
Pout,  136 
Prairie-dogs,  178 
Prawns,  29,  121 
Preen-gland,  184 
Prolegs,  32 
Prongbuck,  91 
Protection,  coloration,  74,  155 

of  larvae,  224 

by  spots  and  stripes,  96 

of  young,  225 
Protein,  185 
Protococci,  117 
Protopterus,  135 
Protozoa,  6 
Puffin,  149,  153 
Puma,  85,  167 
Puppies,  10,  87 
Pycraft,  W.  P.,  102 
Pythons,  146,  196,  197 

QUADRUPEDS,  240,  241 
Quail,  1 06 
Quills,  97,  98 

RABBITS,  3,  46,  72,  75,  77,  149, 
Raccoons,  10,  87,  169,  176 
Rails,  101,  102,  104 
Rainbow,  113 
Rana,  140 
Ratel,  79,  87,  147 

178,231 


INDEX 


Rays,  139 

Reactions  of  living  matter,  236 

Recognition,  71,  131, 145 

Red  deer,  92 

Reed-buck,  89 

Reindeer,  92 

Regent's  Park,  squirrels  in,  147 

Reptiles,  ancestors  of  birds,  159 

mammals,  163 

breeding,  51 

feeding,  196 

incubation,  163 

longevity,  50 

reduction  of  family,  142 

sexual  coloration,  70 

size,  48,  50 

skin  glands,  184 

scales,  8 1 

young,  15,  51,  176,  195 
Respiration,  113 
Rhacophorus,  142 
Rhea,  101,  107,  154,  161 
Rhinoceros,  45,  93,  94,  172,  190 
Rhinoderma,  141 
Rhubarb,  194 
River-hog,  93,  218 
Roan  antelope,  89 
Rock-hopper,  104 

rabbit,  44,  173 
Rodents,  46,  77,  95,  147,  164,  175  177, 

178,  204,  219,  234 
Roe  of  herring,  222 
Roe-deer,  92 
Rollers,  153 

Romanes,  Professor  J.  G.,  201 
Rookeries  of  penguins,  104,  152 
Rose,  W.,  56 
Ruby-flies,  127 
Ruminants,  46,  87,  93,  170,  184 

SABLE  antelope,  89 

Salamander,  2,  17,  40 

Saliva,  nests  of,  152 

"  Sally,"  the  chimpanzee,  209 

Salmon,  52,  135 

Sambur,  92 

Samlets,  52 

Sand-goby,  135 

Sand-grouse,  101 


INDEX 


267 


Sand-martin,  149 

Sardine,  117 

Sargasso  Sea,  137 

Sunflies,  126 

Scarabaeus,  128 

Schizopod,  29 

Scorpion,  121 

Screamer,  102,  104,  153,  157 

Sea,  carnivorous  population  of,  116 

food  supply  of,  117 
Sea-anemone,  118,  236 
Sea-bear,  87 
Sea-birds,  no,  152 
Sea-cucumber,  119 
Sea-gulls,  62 
Sea-horse,  137 
Sea-lions,  10,  87,  214 
Sea-squirts,  118 
Sea-urchin,  119 
Seal,  elephant,  194,  214 
Seals,  10,  42,  87,  214 
Sebaceous  glands,  185 
Secretary  bird,  colour  of  eggs,  154 
Secretion  of  milk,  188 
Seedlings,  food  of,  183 
Selection,  58,  66,  70,  75,  113 
Selenka,  E.,  on  embryology,  9 
Selous'  antelope,  coloration  figured,  90 
Senses  of  vertebrates,  54 
Serpents,  15,  83,  184 
Serval,  85 
Setter,  42 
Sex,  battle  of,  207 

determination  of,  202 
Sexes,  coloration  of,  69 
Sexton-beetles,  129 
Sharks,  eggs  of,  139 
Sheep,  75,  88,  219 
Sheldrake,  107 
Shells  of  eggs,  152 
Shore-birds,  79,  101 
Shrew,  49, 175 
Silkworms,  205 
Silurus,  137 
Silver-fish,  33 
Singing  birds,  101,  108 
Sitatunga  antelope,  90 
Size  and  duration  of  youth,  40,  47,  48 

and  food,  48 


Size  and  temperature,  48 
Skin,  83,  105 

glands,  184 
Skink,  145 
Skunk,  72,  79,  87 
Sloths,  178,  220 
Sloughing  by  snakes,  83 
Slow-worm,  145 
Smell,  sense  of,  243 
Smooth-hound,  139 
Snails,  130 
Snakes,  75 

breeding,  146 

coloration,  72 

eggs,  145 

fascination,  57,  202 

fear  of,  199 

feeding  of,  196,  197 

viviparous,  146 
Snipe,  70,  78,  109 
Sole,  22,  63 
Solenostomus,  137 
Somnambulism,  229 
Song  of  birds,  252 
Sound,  reaction  to,  250 
Sparrow,  98,  115,  116 
Speke's  antelope,  90 
Spiders,   15,   70,  71,  121,  123,   128,  205, 

230,  235 

Spirits  of  youth,  2441  245 
Spoonbills,  154 
Spoon-feeding,  189 
Spots  of  animals,  78,  81-85,  89,  92,  96, 

ii3 

Squirrels,  147,  176,  177 
Stampedes  252 
Starfish,  23,  119 
Starling,  103,  148 
Stick-insects,  124 
Stickleback,  129,  130,  136 
Stimulation,  232,  235,  236 
Stock-breeders,  58 
Stomach,  187 
Stone-curlew,  149 
Stone-flies,  125 
Storks,  49,  no,  153,  161,  242 
Stripes  of  animals,  78,  81,  82,  84,  89,  93 

95,96 
Structure  and  colour,  113 


268  INDEX 


Struggle  for  existence,  36 
Struthidea,  151 
Suckers,  135 
Suckling,  235,  243 
Sugar,  1 86 
Summer-duck,  107 
Sunlight  on  skin,  76 
Swallows,  151,  152,  241 
Swamp -deer,  92 
Swans,  102,  104, 153,  1 61 
Swarm -spores,  232 
Sweat-glands,  185 
Swifts,  102,  103,  152 
Swimming,  240 
Swine,  45,  171,  216 

TABOO,  132 

Tadpoles,  18, 20,  51,  59,  200 

Tail,  17,  97 

Tailor-bird,  150 

Takin,  13 

Talking  birds,  253 

Taming  and  tameness,  204,  205,  207,  221 

Tanager,  100,  112 

Tapirs,  45,  62,  67,  93,  172,  190,  218 

Tasmanian  devil,  180 

wolf,  96 

Tasting,  experimental,  73 
Temperature,  48,  50,  54,  156,  162,  185 
Termites,  125,  132 
Terns,  107 

Thayer,  Abbott,  75,  76,  77 
Thomson,  Sir  Wyville,  119 
Thrushes,  103,  in,  150 
Thylacine,  96,  180,  220 
Ticks,  82 

Tigers,  10,  41,  75,  78,  84,  85,  214,  249 
Timber -wolf,  10 
Tinamou,  101,  107,  154 
Titmouse,  103 

Toads,  15,  51,  59,  76,  141,  140,  184 
Todies,  153 

Tortoises,  15,  143,  195,  IgQ 
Toucans,  66,  153 
Tow-net,  117 
"Towns"  of  beavers,  177 
Tree -bear,  180 
Tree-frogs,  17,  59,  i4O 
Tree-hyrax,  44,  174,  194 


Tree  kangaroo,  179 
Trochophore  larva,  25,  26 
Trogons,  153 
Tropisms,  232-234,  236 
Trumpeter,  153 
Turaco,  154.,  159 
Turbot,  21,  115,  134 
Turkey-vulture,  50 
Turtles,  143,  144 

UMBRE,  150 

Ungulates,  45,  46,  87,  93,  171,  172,  174, 

204,  215 

Unpalatability,  72 
Urodeles,  59 
Utility,  63,  74 

VARIABILITY,  58 
Vegetation,  116,  243 
Veliger,  26 
Vermin,  parasitic,  82 
Vertebrates,  53,  54, 134,  237 
Vicugna,  93, 218 
Vitality  of  youth,  224,  245 
Voice,  1 68 
Vorticella,  236 
Vultures,  49,  103, 105 

WADERS,  107 
Walk,  learning  to,  241 
Wallaby,  179 
Wallace,  A.  R.,  72 
Walrus,  214,  243 
Warrens,  176 
Wart-hog,  93,  218 
Wasps,  73,  127,  128, 132 
Water-beetle,  129 

chevrotain,  93 

deer,  92 

fleas,  120 

fowl,  98 

hen,  io4 

spider,  122 
Weaning,  169,  191 
Weasels,  10,  42,  87,  169 
Weaver-birds,  no,  112 
Webs,  spiders',  122,230 
Weismann,  A.,  57 
Whales,  75,  240 
Whelk,  130 


INDEX  269 

White  ants,  125  Youth,  growth  of  brain,  229 
Whitebait,  137  instinct  in,  238,  243 

Wings,  97,  108,  240  mind  of,  254 

Wolf,  86,  96,  184,  220  purpose  of,  222 

Wolf-fish,  135  spirits  of,  245 

spiders,  123  summary  of,  254 

Woodcock,  78,  1 60  Yung,  E.,  203 
Woodpeckers,  102,  149,  153,  161 
Wood-pigeons,  207 

Worms,  118,  120,  192,  233  ZEBRAS,  45,  75,  95,  115,  172.  217 

Wren,  49  Zebra-duiker,  89 

Zoea,  29 

YOLK,  163  Zoological  Gardens,  London,  38,  41,  51, 
Youth,  definition,  i,  3  86,  124,   147,  150,  158,    165,  166, 

duration,  37,  40,  47,  54,  55.  225  168,  194.  201,  208,  212,  214,  218, 

games,  246  247 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

BIOLOGY  LIBRARY 

TEL.  NO.  642-2532 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


LD2lA-6m-l,'75 
(S33648lO)476-A-32 


General  Library 

University  of  California 

Berkeley 


GENERAL  LIBRARY  -  U.C.  BERKELEY 


*«. 


